Dell (T5400) Power Supply 12 pin to 8 pin socket mod

[mesaritism]

I just wanted to upgrade my dell precision T5400 workstation and got my self in a whole lot of trouble!

Motherboard: 0RW203
PSU: GM869 or H875E-00
Psu wire Harness: YN945

I wanted to upgrade my gpu to Sapphire r9 280x dual-x. It requires 1x6(75w) pin and 1x8(150w) pin power connectors.

These are the PSU's (850W) outpouts
P1 - 24pin ATX Power
P2 - 20pin ATX Power
P3 - 12pin Power
P4 - None
P5 - 6pin Power (2x3)
P6 - 6pin Power (2x3)
3 x Sata Connectors
1 x 4pin Molex ( +1 x 4pin Floppy on the same cable)


Both 24pin and 20pin are connected to the motherboard and if I'm not mistaken the 20pin is utilized for fan power.
My problem is that there are only 2x6 pin connectors and only 1x4 pin-molex (even if I wanted to use two molex and an adapter to produce 8 pin conntector). I don't want to use a 6pin to 8 pin adapter since that equals to a lack of 75w.

There is a strange 12 pin socket that is currently connected to a sata power cable (2 sata plugs on the cable). My question is if I can (remove the sata cable and) connect on this 12 pin socket some kind of 8 pin adapter or even if I can retrofit something my self.
The wattage and amperage have to be the same as a regular 8 pin socket.

Just found the pinout. It's the P3

Thanks to Doramious for the pinout diagramm

PS: Please don't mention the ''get a new psu'' idea.

 

[Dark Lord of Tech]

You can't just get a new PSU , they are Proprietary Power Supplies.

 

[mesaritism]

You can't just get a new PSU , they are Proprietary Power Supplies.

why thank you sir. That's the reason I said don't mention it in the first place

 

[Upgrader3]

There may be some relevant information for you in this thread . . .

http://en.community.dell.com/support-forums/servers/f/956/t/19332502.aspx

With reference to a 650W Dell PowerEdge 1800 Server PSU, participant know as "hurgh" states:

"Turns out the 12 pin connector is just for for power to the SATA drives. This was obvious once I pulled the server apart. I had the two redundant supplies, both failed. Replacing everything with a standard supply and swapping the one purple wire over worked perfectly and my aging server is now up and running again."

In the PE1800, the P3:12-pin [aka P3:2x6-pin] is apparently designed to support as many as 6 server-grade SATA drives/devices, based on:

http://www.amazon.com/Y5562-PowerEdge-6Drop-Power-PE1800/dp/B003FFWONS

If the role of the P3:12-pin connector is comparable in the T5400 and the PE1800, one might infer that the P3 could also support at least that much off the 875W PSU of the T5400 [compared to the PE1800's 650W PSU].

However, will enough power to run at least 6 server-grade Sata drives/devices equate to enough power for your Sapphire r9 280x dual-x?

Alternatively, maybe someone can suggest a simple load-testing technique to address the question on a practical level as opposed to an "estimation" approach?

 

[mesaritism]

Thank you so much for your reply. It gets my hopes up again. I was down this path my self actually.

I went ahead and order the R9280x,
a 6pin to 8pin adapter, http://www.ebay.com/itm/121256470889?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
and a dual sata power to 8 pin adapter http://www.ebay.com/itm/121256470922?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
I hope one of them works. If not, I have a second cpu that I will try to mod to work parallel to my default, just to power up the graphics card.

I took the pc to a couple of local electrical shops and both told me that there should be enough wattage support both form the 6 pin and 12 pin connector, if needed.

I guess I'll be reporting the results in about 10 days when all the parts arrive.

 

[Upgrader3]

Photo of specifications label affixed to Dell GM869 (or H875E-00) PSU:

Pinout of Dell GM869 (or H875E-00) PSU:

Combining the wattage limit info, the amp limit info, the pin breakdown within each connector, and the key that links pins and rails:

Limit T: . . Max output 875W
Limit C53: . Max combined power on +5V & +3.3V
. . . . . . . . . . . . . output is 150W
Limit C12: . Max combined power on +12VA,B,C,D,ED
. . . . . . . . . . . . . is 825W
Maximum amp output [& wattage equivalent] per rail:
+5V . . . . / . 16.0A . . [~80W] . . . linked to P1 & P3
+5VFP . . / . 3.0A . . . [~80W] . . . . linked to P1
+12VA . . / . 18.0A . . [~216W] . . . linked to P1 & P5
+12VB . . / . 18.0A . . [~216W] . . . linked to P2 & P3
+12VC . . / . 18.0A . . [~216W] . . . linked to P2
+12VD . . / . 18.0A . . [~216W] . . . linked to P6
+12VE . . / . 18.0A . . [~216W] . . . linked to P1 & P2
-12V . . . / . 0.2A . . . [~2.4W] . . . . linked to P1
+3.3V . . / . 30.0A . . [~99W] . . . . linked to P1

[NOTE: . The estimated maximum wattage output of any given rail [3rd column] is only achievable if other rails are not too heavily loaded. . Thus the third column sums to considerably more than 875W.]

I'm not a PSU or load-analysis expert, so I am going to pose my thoughts here as questions rather than statements . . .

In view of the above information . . .

Can it be said, at least very roughly, that...

1) ...Connector P3 can convey a goodly portion of the 216W limit (via the +12VB rail) plus a goodly portion of the 80W limit (via the +5V rail) to the videocard's 6-pin input, PROVIDING THAT loads elsewhere in the system [especially loads upon connector P2, which are also bourne by the +12VB rail] are well behaved.
?

2) ...It's better to serve the vidcard 8-pin input from connector P6 than from connector P5, since P6 is the only connector linked to its +12VD rail, while both P1 and P5 are linked to their +12VA rail
?

3) ...Connector P6 can convey much of the 216W limit (via the +12VD rail) to the videocard's 8-pin input, PROVIDING THAT loads elsewhere in the system are well behaved.
?

I would appreciate hearing feedback from those who do have knowledge and experience in PSU design, function, load-analysis, and real-world behavior.

 

[mesaritism]

You comments are great even in the form of questions.
I'd like to add a question relative to Upgrader3's question no1

- If I conclude in using the P3 connector should I disconnect the +5v, +3.3v rails and utilize only the +12VB rail?

 

[Upgrader3]

There are only 3 hot pins in the 8-pin PCI-E Aux 150W P/S connector, and the voltage on all 3 is +12V:

http://www.tomshardware.com/gallery/PCI-Express-8-pin-2x4-auxiliary-150W-power-supply-connector,0101-312645-10124-0-0-0-jpg-.html

Therefore the Sata-to-8pin adapter needs only 1 yellow wire (+12V) and 1 black wire (GND) from each of the two male Sata connectors [the third of the 3 hot pins is fed by a little yellow jumper].

The adapter neither needs nor deploys any red (+5V) and orange (+3.3V) wires, and by omitting them, the adapter itself "disconnects" the +5V and +3.3V rails at each of the SATA female/male junctions:

. . . . . . . . 5=== SATA ===2
. . . . . . . // . . . . f<>m . . . . \\
. P3 ===|| . . . . . . . . . . . . . ||=== 8Pin-Vid
f<>m . . .\\ . . . . . . . . . . . . ,// . . . . m<>f
. . . . . . . . 5=== SATA ===2
. . . . . . . . . . . . . f<>m

5 = 5 wires from P3 to each SATA [via Dell adapter]:
. . 1x Red (+5V)
. . 1x Yellow (+12VC)
. . 1x Orange (+3.3V)
. . 2x Black (GND)

2 = 2 wires from each SATA to 8Pin-Vid [via StarTech adapter] :
. . 1x Yellow (+12VC)
. . 1x Black (GND)

----------------------------------

BTW, here is a single-Sata (as opposed to a dual-sata) version of the adapter that is available with either a left or a right 90-degree connector:

http://www.ebay.com/itm/NEW-SATA-15-PIN-TO-ONE-8-PIN-PCI-EXPRESS-90-DEGREE-LEFT-CABLE-MADE-IN-USA-/251341326078?pt=US_Power_Cables_Connectors&hash=item3a851c46fe

http://www.ebay.com/itm/NEW-SATA-15-PIN-TO-ONE-8-PIN-PCI-EXPRESS-90-DEGREE-RIGHT-CABLE-MADE-IN-USA-/261288926731?pt=US_Power_Cables_Connectors&hash=item3cd6089e0b

In the case where both of the Sata connectors of the dual adapter are getting their power via the one P3 connector (and via the same +12VB rail), there is no advantage to having the dual configuration versus the single configuration -- and some potential disadvantage since the singe-Sata adapter would leave the other Sata connector free to power a Sata device.

 

[mesaritism]

So to get this straight I thought a bit of illustration should help.
I'm sorry in advance of any of the following illustrations are wrong. I have no electrical experience what so ever so please be lenient.

To clarify things a bit before i proceed I just found out that:
- The sata power cable utilizes only ONE +12v (yellow) wire from it's respective rail. (This must be common knowledge)

- Dell PD145 12 pin to Dual Sata adapter has the +12v (yellow), +5v (red) wires of each sata conncetor connected to different pins on the 12 pin connector. (the +3.3v wires are connected on the same pin)

Following are the adapter connection Illustrations:

Using the SATA POWER to 8 pin connector adapter that you recommended
http://www.ebay.com/itm/NEW-SATA-15-PIN-TO-ONE-8-PIN-PCI-EXPRESS-90-DEGREE-LEFT-CABLE-MADE-IN-USA-/251341326078?pt=US_Power_Cables_Connectors&hash=item3a851c46fe
will have the following setup
P3: 1x +12v pin(pin3)<--1 wire-->SATA power: +12v pins(pin13,14,15)<--1 wire-->8pin PCI-e: 1x +12v pin(pin1)
P3: 1x GND pin(pin4)<--1 wire-->SATA power: COM pins(pin10,11,12)<--1 wire-->8pin PCI-e: 1x GND pin(pin5)
8pin PCI-e: +12v(pin1)<-->+12v(pin2,3),GND(pin5)<-->GND(pin6,7,8,4SenseI)
This means all the wattage supllied is delivered from a single wire.

Using the DUAL SATA POWER to 8 pin connector adapter that I purchased
http://www.ebay.com/itm/121256470922?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1497.l2649
will have the following setup
P3: 1x +12v pin(pin3)<--1 wire-->SATA powerA: +12v pins(pin13,14,15)<--1 wire-->8pin PCI-e: 1x +12v pin(pin1)
-----1x +12v pin(pin2)<--1 wire-->SATA powerB: +12v pins(pin13,14,15)<--1 wire-->8pin PCI-e: 1x +12v pin(pin3)
P3: 1x GND pin(pin5)<--1 wire-->SATA power: COM pins(pin10,11,12)<--1 wire-->8pin PCI-e: 1x GND pin(pin5)
-----1x GND pin(pin4)<--1 wire-->SATA power: COM pins(pin10,11,12)<--1 wire-->8pin PCI-e: 1x GND pin(pin7)
8pin PCI-e: +12v(pin3)<-->+12v(pin2),GND(pin8)<-->GND(pin7),SenseI(pin4)<-->GNDSense0(pin6)

Using a P3 to 8 pin PCI-E direct connection mod (eliminating the Dell PD145 and sata power to 8 pin adapter)
will have the following setup
P3: 1x +12v pin(pin3)<--1 wire-->8pin PCI-e: 1x +12v pin(pin1)
-----1x +12v pin(pin2)<--1 wire-->8pin PCI-e: 1x +12v pin(pin2)
-----1x +12v pin(pin9)<--1 wire-->8pin PCI-e: 1x +12v pin(pin3)
P3: 1x GND pin(pin5)<--1 wire-->8pin PCI-e: 1x GND pin(pin5)
-----1x GND pin(pin4)<--1 wire-->8pin PCI-e: 1x GND pin(pin6)
-----1x GND pin(pin10)<--1 wire-->8pin PCI-e: 1x GND pin(pin8)
8pin PCI-e: SenseI(pin4)<-->Sense0(pin6),GND(pin7)<-->GND(pin8)

These are my questions:
-Isn't the dual SATA power to 8 pin PCI-E adapter better then the single Sata power adapter for my case? Isn't it safer to deliver the wattage using two wires instead of one?
-Is the final solution, the direct connection between P3 and 8 pin PCI-E, the best solution after all? Isn't it safer to utilize as many wires sa possible on a single rail?
-Is connecting SenseI with Sense) on the 8pin PCI-E the correct setup? If not what is the correct setup?


All this is theoretical in case I need to use the P3 connect to power my graphics card.
As you mentioned before...''Connector P6 can convey much of the 216W limit (via the +12VD rail) to the videocard's 8-pin input, PROVIDING THAT loads elsewhere in the system are well behaved''.
That's why I'll probably be using the 6pin to 8pin adapter on the P6 and the P5 to power my graphics card

 

[Upgrader3]

When I stated that "there is no advantage to having the dual [Sata] configuration versus the single [Sata] configuration", I was assuming -- without bothering to do any calculations -- that the transmission losses and heat dissipation of either configuration would not differ significantly.

Ohm's Law can be used to calculate:

- the voltage drops on the three wire sectors from the PSU to the Vidcard's 8-pin connector
- the associated power transmission losses, and resulting heat generation

Closed-DC-circuit diagram for the +12VB rail with the Dell PD145 adapter installed on the P3 connector, and the single-Sata [sS] adapter plugged into the Vidcard's 8-pin input:


|------R1 [hot]------<>------R2 [hot]------<>------R3 [hot]------|
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
+12VB Rail . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vidcard_8pin
| . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .|
|------R1 [gnd]------<>------R2 [gnd]-----<>------R3 [gnd]-----|

|______________| . |_____________| . |_____________|

. PSU to P3 . . . . . . . . . P3 to sS . . . . . . . . . . . sS to 8-pin
. 1 x 16(?)awg . . . . . . 1 x 16(?)awg . . . . . . . 3 x 18awg
. A = 1.31 mm2 . . . . . . A = 1.31 mm2 . . . . . . A = 3 x 0.82 mm2
. 1.2 ft (two-way) . . . . 1.6 ft (two-way) . . . . 1.0 ft (two-way)

R1 [hot] - represents a single hot wire
R1 [gnd] - represents the complementary single ground wire

R2 [hot] - represents a single hot wire
R2 [gnd] - represents the complementary single ground wire

R3 [hot] - represents the 3 parallel hot wires ["3-lane highway"]
R3 [gnd] - represents the 3+ complementary parallel ground wires

The lengths are rough estimates, and can be corrected as needed.

Note that the cross-sectional area [ A ] shown for the single-Sata [ sS ] sector equals 3 times the cross-sectional area of a single-wire, and computes to 2.46 mm2.

To calculate the voltage drop associated with the resistance in the wiring, assume the card is drawing 12.5A at approximately 12V, thus drawing approximately 150 Watts of power at its 8-pin connector.

[I write "approximately" 150 Watts, because -- if the voltage from the rail holds steady at 12V, and the current drawn by the card is steady at 12.5A -- then there is a voltage drop over the wiring of 0.16V (see the results further below), and the card's 8-pin input only sees a voltage difference of 11.84V. . Thus the wattage actually delivered turns out to be only about 148 watts, with about 2 watts being dissipated in the wiring. . The card and the wiring together would have to draw around 12.67A (through the 8-pin) at to get a true 150W (11.84V * 12.67A) for the card.]

V = I * R

I = constant at 12.5A, i.e. the current flow is the same through every element of the circuit

V1 = 12.5A * R1
V2 = 12.5A * R2
V3 = 12.5A * R3

The voltage drops can be calculated using this online-calculator:

http://yeroc.us/calculators/wire-resistance?material_resistivity=1.68E-08&web_resistivity=&gauge=18&web_area=&area_factor=1E-06&web_length=1&length_factor=0.304878&current=12.5&submit=Calculate

This calculator uses the two-way or "round-trip" format. . It gives the following results for resistance, voltage drop, and power dissipation:

2*R1 = 0.005 Ohms . 2* R2 = 0.006 Ohms . 2*R3 = 0.002 Ohms

2*V1 = 0.059 Volts . . 2* V2 = 0.078 Volts . . 2*V3 = 0.026 Volts

2*D1 = 0.734 Watts . 2* D2 = 0.978 Watts . 2*D3 = 0.325 Watts

In the single-Sata adapter configuration, the total watts dissipated between the +12VB rail and the Vidcard is about 2 Watts. . At 6 Amps, it would be about 1 Watt, whereas at 18 Amps it would be about 3 watts.

Doubling or tripling the number of "wire-lanes" all the way to the rail (and/or rewiring with 14awg or 12awg) would be able to cut the losses by a half or a third, but.... how serious is a loss of 2 watts?

Small terrarium heaters start at around 4 watts. . .
http://www.amazon.com/Zilla-Terrarium-Heater-4-Watt-4-Inch/dp/B005SRVNU6

Suppose a 12V PSU powers a 12.5 Amp load through a pair of 6"-long hook-up wires -- of unspecified AWG. . How thin would the wires have to be, to become "too hot to touch"?. . Maybe if they were thin enough to dissipate about as much heat as an incandescent light bulb? . . With that in mind, I played with the online calculator, and found that if the AWG is dialed down to 36, the pair of 6" long 36awg wires (0.005" diameter) will dissipate about 80 Watts between them, or 40 Watts each.

An 18awg wire is 1.024mm in diameter and has an Area of 0.82 mm2.

A 36awg wire is 0.027mm in diameter, and has an Area of 0.0127 mm2 -- about 40 times thinner in diameter, with about 65 times less Area, compared to an 18awg wire.

 

[Doramius]

I'm trying to find the physical specs for this PSU to identify the amperage. I think it was between 20A-26A per P5 & P6 rails. Since they're already 12V connections, you might find it better and easier to find a 6-pin to 8-pin PCI-E adapter connector, or building the P6 yourself. Here's the pinout of traditional 12V PSU connectors. Note that sometime the PCI-E connectors are sometimes called PEG-6 or PEG-8 (PEG = PCI-Express Graphic) connectors. Some connectors have adaptive spilts, that are indicated in the below diagram.

 

[David Grohl Z]

Is it possible to use 2x 6-pin to 8-pin to get a 150W 8-pin, and a molex to 6-pin to get a 75W 6-pin?

 

[Doramius]

Is it possible to use 2x 6-pin to 8-pin to get a 150W 8-pin, and a molex to 6-pin to get a 75W 6-pin?

It all depends on the PSU ratings, and where the rails lead back to. This type of PSU has several independant 12V lines. They may be filtered differently. Most of the time it shouldn't cause any problems, but if one rail fails, and another does not, it can cause stability problems. Some hardware already recognize this and have 2 separate ports for voltage in isolated paths. That's the least of your problems.

What you're asking is "Can you boost the power rating by mixing 2 rails?" You'd have to use Ohms law with info of the load device to get a correct number. E=IR ; P=IE ; E=Voltage, I=Inductance(amperage), R=Resistance(load), P=Power(Wattage)

Here's a diagram with more mathematic info:

 

[mesaritism]

Thanks everyone for your time and answers. They are really priceless.
Sorry for my delayed reply but I had run in some serious family health problems.
Nevertheless I didn't find any time to do any of the necessary calculations but

I installed a new Gainward GTX 770 Phantom 2gb in my system.

So far I haven't had any rebooting or freeze screen issues. I tested the card both with Rhinoceros 3D and Battlefield 4. The gpu is able to max out it's core and memory and core usage. So I think this is a good sign power-wise.

The gpu has one 6-pin and one 8-pin connector. I ultimately used the P5 for the 6-pin connector and the P6 with a 6 to 8-pin adapter for the 8-pin connector.

The gpu has a voltage monitor utility, among others and It states that the 'Base Voltage' for the gpu is 0.887V. I've seen it bump up to 1.2V while stressing the card with Bf4. I don't know if it can go any higher and how the voltage is translated in Wattage. I also think that this sensor is exclusively responsible for monitoring the gpu's core voltage and not the entire system (memory and fans).

Having that said, I'm having some performance issues regarding frame rates. The fps hangs around 25-40 (highest around 80 but scarcely)fps while benchmarks suggest that it should be around 40-80. I noticed that the frames massively drop in areas that are heavily populated with geometry (buildings) and debris particles in the air. As I said The card can max out its core usage and clock but the cpu core usage hangs at about 60% and never exceeding 70% for any of its cores. I also noticed that only 2 of the 8 cores are heavily used while others have a constant lower usage. Lowering the graphics options to the 'low' preset will only gain me at about 10 fps. That made me think that this is a cpu bottlenecking issue. I just tried removing one of my two cpu's to see if the system is under powered using both cores and there's huge difference in cpu usage. Now all cores are almost constantly up to 100% but gpu usage wont go passed 70%. Frame rate is even worse and lagging at 23-34 fps.
I will start a new thread specifically for the frame drop issue as it's starting to be a little unrelated to this original thread.

If you have any suggestions for monitoring utilities that would help in finding out if my system is under powered please feel free to post them. I'm already using HWinfo, Gainward's EXPERTtool and fraps but don't know what to make of all the data.

Thank you for all your help. It's greatly appreciated

PS: I would love to hear performance benchmarks from people who own similar system but with higher clocked cpu's

 

[GrinningB]

We certainly are starting to feel the age on this system! LOL!

I got myself in the same boat by deciding to drop the money and get the Radeon R9 290. It arrived missing pieces so I can't even test currently BUT I think I may have found the culprit to your performance issues.

Our systems were designed to provide 75 watts through those 6 pin P5 and P6 connections. You're asking P6 to give 150 watts. That might just be the problem with your performance and given the age of our systems might just be dangerous as well.

My solution right now is to either make a custom adapter off of P3 and connecting it to the 6 pin video card connection OR use your dual sata to atx idea but again for the 6 pin only. For the 8 pin, buying a dual 6 pin atx to single 8 pin which will combine P5/P6 and give me the 150 watts I need fairly easily.

If that doesn't work, I'm tempted to try the purple wire swap with a new psu rated at least 1000 watts - or I may just hold on to everything and save my pennies for a new build. LOL!

I did notice a few discrepancies with your math though. You state getting 216 watts from P6 (d-rail). All things being equal, each rail only provides 165 watts of 12v power. I get this from the actual label on the psu. 150 watts goes to supply lower voltages and 825 goes to 12v spread across 5 rails. 825/65=165.

I still admit to some concern about being able to power this monster though. My motherboard says the card can draw 75 watts from the pci slot itself and with my proposed connections I'm pretty sure I can give it the 225 watts it's asking for on top. 300 watts total. Then I read this card can draw 400+ at full bang. Dell.com tells me the slot can provide 150 watts, so here's hoping!!

 

[GrinningB]

I spent hours trying to figure out how to get what I wanted out of our PSU. Managed to come up with the idea of repurposing a 24 in ATX motherboard cable by pulling the pins out o fthe male end and using that to plug all the 12v+ from P3, P5 and P6 as well as all the grounds, and combining the leads so the original P3 and P6 leads fed to a 8 pin PCIE connector with the extra ground. The remaining leads wired into a re-used p6 connector. Even thought to re-use the p5 connector for the remaining 5v and 3.3 v leads going to p3. Ooh it was elegant. Now I had the untouched P1 and P2 powering the motherboard. P5 would be tied off and become unused. I would have brand new 24 pin connector that fed both power pins on the card and make the case so much cleaner.

Then I priced everything out through Amazon and NewEgg - since I needed a crimping tool to combine the leads on the 8 pin the total was just under $100.

For $35 I ordered this and will leave my wiring harness alone now...
http://www.newegg.com/Product/Product.aspx?Item=17-101-044

 

[GrinningB]

Amazon delivered me the missing cables yesterday so I was able to finally install the card. ~I asked for a 6+2 to 6+2 adapter~ I have some interesting results now...

I should note that my system is maxed with 2x4core Xeon performance (max 130 watts each) with 32 gigs of ram, 2 ssd's, a SATA drive and the DVD drive. (what this means is from the factory Dell would probably have bumped this up to the 1000 watt supply option with all this and the original factory Quadro graphics card had I ordered it this way)

Running the card off P5 for the 6 pin and P6 for the 8 pin. Drivers installed, bios flashed and running the card not overclocked and in silent mode (low power). Fire up GPU-Z and run the same tests in Furmark I did on my old video card. Okay, lots better performance - happy with the purchase on that count. Looking at the logs in GPU-Z and I start seeing the weaknesses....

The highest voltage the card ever saw throughout my testing was 11.88 volts. that voltage dropped to 11.75 when I put the card through the Furmark test - regardless of test settings. Lowest wattage used by the card shows 8.6. Highest shows 267 watts. That's alarming enough for me to not even try testing in high performance mode let tweaking the overclock. Given the card is pulling 75 watts from the graphics slot, another 75 watts from the P5 to 6 pin power leaves 167 watts being pulled from P6!!!! And my voltage is dropping from the PSU meaning I don't have the overhead to just pull from 2 rails, maybe not even if I mod and pull from 3 rails.

I'll let you know what the results are when the booster power supply comes in next Wednesday and I get it installed to boost P5 and P6...

 

[GrinningB]

*UPDATE* and revision of opinion to OP

Aux psu came in. Installed as a booster (P5 and P6 plugged into 2- PCIE6 of booster, 2- PCIE8 from booster to both connectors of GPU with appropriate connector/adapter)BOOT MACHINE....... Flashing power button and error. UNPLUG EVERYTHING!!!! Test the booster and it's outputting 12.7 VDC which throws the power alarms on the motherboard. Reconnect using P6 to GPU and pulling 8pin power from the booster. Machine boots just fine. Okay, so I need to rework the voltage regulation on the booster so output voltage matches the psu. Radioshack to the rescue, $15 and I mod the booster. (not for the faint of heart). Reinstall the booster AS a booster P5&6 to booster, GPU powered FROM booster. IT WORKS NOW!!!! WOOT WOOT!!! Original power supply now runs much cooler without the extra load and full performance check on the GPU work flawlessly - I even can play with overclocking!

Interesting sidenote. After running the card just from the internal PSU a few days it's power usage actually went down without affecting performance. Must be a "burn in" thing. But my PSU was running a lot hotter so I knew I was pushing it running this card regardless.

Happy with everything, I button up the case. Now I start having some problems. Figure out that it's heat related. I'm not getting the cooling I need on the GPU! Part of the problem is the aux PSU cools itself with outside air and dumps that hot air INSIDE THE CASE. Okay, pull it out and reverse the fans. Now it exhausts out the the front. Problem is now PARTIALLY corrected. With the case closed, there isn't enough cooling power designed into the top portion of the case to effectively cool my GPU!!! My new card is just a space heater in disguise and I'm going to have to deal with that somehow...

This is where I revise my opinion to the OP. Your card may be throttling itself down so it doesn't overheat. Best test for that would be to pull the cover off (maybe even set a fan up to blow into the case) and play your game. If you get better performance, you probably need to look in the same direction I am of adding some side panel cutouts, adding fans and porting those fans to blow directly at my GPU.

Now, onto other interesting tidbits I've run across. You CAN upgrade your PSU!!! The upgraded PSU available from Dell (1000 watt) is the exact same model as the STANDARD PSU in a T7400. Quick search on Ebay and I found used from $30 w/o harness. Get one and it's really plug and play compatible with your system!

Now as for powering your GPU, I still think pulling 150 watts from P6 is just asking for trouble. If you are powering hard drives off the P3 harness, reconfigure those drives to the drive cage by the PSU or switch to an external drive to meet that need. Now comes the fun part - if you can do this yourself it's easier - but get/make a custom power harness to combine P3 and P6 and power your 8pin GPU connection from this. Essentially it would be a 8 pin PCIe female connector with double leads to pins 1-3, 5-7 and single lead from 4 and 8. Now take one each of the 1-3 leads and pin them to a 12 pin MALE ATX connector at 2, 3 an 9. Take one lead from 4-6 and pin to the 12 pin male at 1, 4, 10. Pin the 4 and 8 from the 8 pin to 5 and 11 of the 12 pin male. Now pin the remaining leads to a MALE 6 pin PCIe (positive to 1-3, negative to 4-6). Plug P5 to your card, P6 to the male 6 pin on your new harness. Plug the 12 pin to P3 and finally back to your GPU with the 8pin female. Boom you combined P6 to P3 to power the GPU. I would STILL do this even if I stuck a 1000 watt PSU in...

 

[mesaritism]

EDIT*

[...]
Aux psu came in[...] IT WORKS NOW!!!! WOOT WOOT!!! Original power supply now runs much cooler without the extra load and full performance check on the GPU work flawlessly - I even can play with overclocking!

GREAT NEWS MAN!. Thanks for providing a solid solution. The supplementary PSU idea sounds like the safest most reliable and cost effective way to go. I would love to get my hands on one of those.
I live in Greece and unfortunately newegg doesn't ship internationally.
http://www.newegg.com/Product/Product.aspx?Item=17-101-044
I will continue my search in hope to dig one up at an affordable price.
I did find some other models online but were out of stock or in-affordable (I hope my english here's ok)
FSP Group Booster X5 450W:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817104054
FSP Group Booster X5 300W:
http://www.newegg.com/Product/Product.aspx?Item=N82E16817104019&cm_re=FSP_Group_Booster_X3-_-17-104-019-_-Product

[..]look in the same direction I am of adding some side panel cutouts, adding fans and porting those fans to blow directly at my GPU.

I saw a post a while back with a guy that had done the exact same thing you're considering with the side fans and had good results
http://www.overclock.net/t/1444368/two-gtx570s-in-a-dell-t5400-heat-issue

Now as for powering your GPU, I still think pulling 150 watts from P6 is just asking for trouble. If you are powering hard drives off the P3 harness, reconfigure those drives to the drive cage by the PSU or switch to an external drive to meet that need. [...]get/make a custom power harness to combine P3 and P6 and power your 8pin GPU connection from this. Essentially it would be a 8 pin PCIe female connector with double leads to pins 1-3, 5-7 and single lead from 4 and 8. Now take one each of the 1-3 leads and pin them to a 12 pin MALE ATX connector at 2, 3 an 9. Take one lead from 5-7(correction) and pin to the 12 pin male at 1, 4, 10. Pin the 4 and 8 from the 8 pin to 5 and 11 of the 12 pin male. Now pin the remaining leads to a MALE 6 pin PCIe (positive to 1-3, negative to 4-6). Plug P5 to your card, P6 to the male 6 pin on your new harness. Plug the 12 pin to P3 and finally back to your GPU with the 8pin female. Boom you combined P6 to P3 to power the GPU. I would STILL do this even if I stuck a 1000 watt PSU in...

Very nice directions and smart thinking! You had a little typo which I corrected (in red). If that wasn't a typo please tell. I took the liberty at drawing up a sketch in photoshop so we make clear we understand each other.

Because a female 12pin ATX connector is very hard to come buy, I took a closer look at an old busted PSU I had. If you cut the standard 20pin ATX connector (that usually plugs on the motherboard) vertically between pins 4,5 and 14,15 the left half (a bit larger than half actually) will end up looking exactly like the pins of the P3 12pin ATX connector. Cutting the plastic connector is easy with a small steel saw. Just be careful and cut directly through the middle. You don't want to expose the pins by cutting into their chamber. I already have a dual male 6pin PCI-e to single female 8pin PCI-e adapter. If I remove the pins carefully from one of the 6pin adapters I can reconnect them on the new hacked 12pin ATX as you described and voila! It's ready to test your theory for combining P3&P6.*EDIT: Because its a 6pin male adaptor to 8pin I will have to re-crimp with female crimps all the wires that I need to remove from one of the 6pin male connectors and connect to the hacked 12pin ATX. Painful, time consuming process.
I will try this out as soon as possible.

Now for the bad news!
Stupid of me but when I received the GTX770 I never actually took the time to take a furmark test and see at the wattage consumption. Like a little kid I saw the gpu running battlefield and I thought all is well.
I did some tests with furmark and monitored with either furmark's integrated gpu-z or HWinfo. MAXIMUM WATT CONSUMPTION = 84W!!!. It won't push beyond that and the worst part the gpu reaches 90 celcious under a minute. As you said the motherboard is capable of providing 75W to the gpu through the PCI slot. That fact kept me thinking if the pci-e connectors from the psu where giving any current at all. I took the gpu out to examine and take to a local pc hardware shop to check on a proper rig. Don't lough but both shops I took the gpu to didn't have any capable machines to test the gpu?!?!?!? (Yes I live in a small place) When I brought the card home I noticed a translucent white residue right above the pci-e connectors. The internet describes this as a solder flux residue and >normally< it's no reason to worry about... or is it? My case is not as bad as this one:
http://forums.overclockers.co.uk/showthread.php?t=18191115

Questions:
Is there a way to check individual power input from each pci-e connectors on the gpu?
Is there a way to check output power on any psu connector?
How can you monitor psu temperatures?
What kind of gpu do you (GrinningB)have?

 

[GrinningB]

Ha! Thanks for catching my typo but I'm going to throw one back at you! In your illustration of the 8 pin pci-e, Pin 4 is negative and you have it color coded as positive. Wired correctly though as far as I can tell!! You understand my thought process here! Since you have the ability to recrimp, you may get cleaner results by rewiring directly from the internal connection of the PSU and deleting the 12 pin altogether. Re-pinning is so much fun, NOT!!!! I feel your pain. Consider unplugging the harness from all connections and remove the PSU. Working inside the case is just more aggravation than it's worth.

Finding the drive bay PSU was not as easy as it sounds for me either. I guess there is not a huge demand for this type of solution any more so vendors discontinued production. The one I ended up getting is not of the quality I really would like and I had to rewire and reconfigure to make it meet my needs. It has very small fans to cool it, which are noisy at full speed. Possible alternative for you could be this: Remove the internal CD/DVD drive(s) and use the 2 top drive bays to mount a standard ATX PSU of about 450W?? It wouldn't necessarily be easy, but it could be done. I may end up doing this myself and replace the power components of the alternate PSU I got. If you want to discuss that option, email me! grinning.b@gmail.com

As for your temperatures. My GPU ran at 90C before I managed to improve cooling. At idle it ran 75C and under any load it quickly shot to 90C or more. My GPU will fault at 95C (and I proved it sadly), so running at 90C is way too close for me. I did end up adding fans to the side cover, reversed the front fans to blow out the front (literally remounted the fans backwards) and added baffling to direct the hot air from the GPU to the bottom of the case. My idle temperature is now 45C. Now I've never seen it go over 75C while gaming and Furmark got it to 85C. Having a 10 to 20 degree buffer to the maximum temperature makes me happy. I set my GPU fan speed to make a big jump to full speed at 80C so I can tell when it gets hot while gaming without having to monitor it myself. Normally my fans run about 50-60%, which I can barely hear.

Solder flux. It could also be a failure of the resin coating common on circuit boards after flux removal. Try cleaning it with alcohol. Light use of alcohol and some rubbing will start to remove flux residue but will not dissolve resin coating. If it comes off, keep going and get off as much as you can. Concentrate on making a break between connections more than getting it all off. If alcohol does nothing, STOP!! Dry the card thoroughly before use. You don't want moisture getting below the resin. My cheapness says to give it a light coat of clear nail polish to seal it, but I have not researched the subject to know if that is safe or not.

Now for answers:

Individual usage at each pci-e connection. I don't know of an easy way, but I do have ideas (email me if you want them). I have to trust that the GPU manufacturer wired these cards to draw power according to the connection specifications. 75w from the card slot is pretty standard as is the 75w from the 6 pin pci-e although it *can* provide more wattage within reason. The pci-e 8 pin is rated at 150w and again *can* provide more within reason. So my very unscientific method for checking power is to watch GPU-Z total wattage. If my wattage stayed below 225w total, I was drawing no more than 75w per connection. Anything OVER that and I have to hope the card is smart enough to pull the additional wattage from the 8-pin. I've never managed to get over 300W total so I have no idea what my system would do. I also know I'm relying on software to tell me the power usage and there is an error factor involved. I saw a .5V difference between what GPU-Z reported and what my multimeter read just in the voltage.

Checking power from the psu. All I did was use my multimeter to probe the connections at idle then again under load to check the difference in voltage. I don't have the equipment to check wattage use. I never saw an alarming voltage drop, so I trust that my PSU is performing pretty well for being as old as it is!

Monitoring PSU temperatures. I have a little magnetic thermometer that I simply stuck to the back of the PSU to monitor air temperature coming out. My multimeter also came with a temperature probe which I used as well. Room temperature was 78F (25.5C) and air temperature from PSU at idle was 85F (29.5C). When I was powering the card only from the PSU the temperature under load shot up to 110F (43.5C). Adding the secondary PSU and the temperature never went over 95F (35C).

As for my GPU. I bought a Gigabyte Radeon R290. It's slightly overclocked and came with the Windforce triple fan system to cool it. Comparable to the GTX780 and allows me to run my games at ultra settings. My only complaint is the heat output, but that's a typical complaint for the Hawaii GPU chip

 

[GrinningB]

Also, my T5400 came with the SATA dual power harness that connects to P3. My solution to the OP reuses the 12 pin female connector from that harness by unpinning everything from it I know, repinning is so much fun!!

 

[GrinningB]

**LATEST UPDATE**

The drive bay PSU got on my nerves after a while. It has 40mm fans to cool it and they're noisy at just about any speed. So, Ebay mined and found a T7400 PSU with harness for $32. Fits perfectly, except it's about 25% longer. The harness itself is interchangeable with either PSU, with a LOT more power outputs/SATA etc. (perfect for connecting the extra fans I've had to install to keep things cool) The bonus here is an 8 pin ATX connector with a 6 pin PCI-E piggybacked. I repinned that to wire an 8 pin PCI-E connector and that was it! Wish I'd done this first.

SO the easiest answer is to get a T7400 PSU harness and a male 8 pin PCI-E connector, do a little repinning and you're good to go. If you're worried about having enough power, get the T7400 PSU with harness.

 

[mesaritism]

GrinningB thanks for all your input and helpful advises. This is starting to be a really decent thread.
You're absolutely right. I will email you about specific , not-so-related questions to avoid cluttering the thread. Also I will correct the diagram error asap. I will test everything you recommended as soon as I can get to it. I'm currently in between visitors and a thesis, so that might take a while

Great to know that the T7400 Psu works on the T5400 system out of the box!
Just to confirm it is the same psu that you mentioned in an earlier post, that this was a 1000w power supply right?
I would be wonders to know more data about this dell transplant:
Is there a problem for fitting the psu in the case, because of it's extra 25% length? Is there an issue with air exhaustion?
How much is your actual wattage consumption from the gpu with the new psu?
Is the rest of the system working ok?Are both 24pin and 20pin ATX on the motherboard powered?
For last, it's more of a favor than a question: Is it possible you list the connectors of the T7400 PSU? I couldn't find any info on the web for the connectors or the pinout.

Again thanks for all your priceless help

 

[rickiricki]

SO the easiest answer is to get a T7400 PSU harness and a male 8 pin PCI-E connector, do a little repinning and you're good to go. If you're worried about having enough power, get the T7400 PSU with harness.

.... so you mean : just to buy cables of PSU of T7400 and put them into PSU of 5400 ??? and it could work ?

Great to know that the T7400 Psu works on the T5400 system out of the box!

... now i am not sure, if tehe T7400 can be fitted inside the T5400 case on the place of original PSU or not ?

For last, it's more of a favor than a question: Is it possible you list the connectors of the T7400 PSU? I couldn't find any info on the web for the connectors or the pinout.
[/quotemsg]

... find T7400 userguide, and you will see the full list of cables it has...

 

[Doramius]

The connectors posted are from one of several PSU diagrams I've created. I don't know of a T7400 pinout available online, and I don't currently have one where I've tested the voltages. However, I do know most of Dell's color coding. If you could post pictures of the PSU labels, cables & connectors, I might be able to create the pinout for you.

However, I'd suggest creating a new topic and messaging me a link to it. I do try to respond to messages when I can, but my profession requires a bit of travel, so I apologize in any delay responding or updates. It's usually not too long.