1kW PSU too weak for GTX 770?

[ianhuysman]

So about a week ago I put a GTX 770 in an older Dell computer, everything works fine but when I play some more demanding games (fallout 4, skyrim, gta 5,...) and everytime something happens in the game my system crashes. I tried reinstalling my video drivers (using DDU) but it has no effect. After doing some research I found out a GTX 770 requires 42amps. When I look at my PSU it says it can only deliver 18A on the +12V rail. I don't know if I'm reading it wrong because I don't know how these rails work in PSU's. I've put a picture of the label of my PSU below.

 

[Snipergod87]

Your PSU has 5 12v rails (which honestly is terrible) with a max is 18A each If you split the 12v rails for the 2 connectors to the GPU (IE one connector 12VC and the other 12VD you might be ok)

 

[kanewolf]

As long as the 6 pin and the 8 pin supplemental power come from two different rails you should be fine. 18A on a 12V rail is 216W. The 8 pin PCIe supplemental power only has to supply 150W. You should be OK.

 

[ianhuysman]

Your PSU has 5 12v rails (which honestly is terrible) with a max is 18A each If you split the 12v rails for the 2 connectors to the GPU (IE one connector 12VC and the other 12VD you might be ok)

That is what I did they're on 2 different 12V rails (I guess). The 6pin is on 12VD and the 8pin is on 12VE. So according to you there shouldn't be any power issues? Also here are some more details of the PSU:
http://imgur.com/a/n2olD
http://imgur.com/a/qVfBL

 

[rcald2000]

ianhuysman I agree with Snipergod87's assessment. For my own curiosity, what model of Dell computer did this PSU come in?

 

[turkey3_scratch]

Can you elaborate on what you mean when you say your system crashes? That can be interpreted in many ways.

 

[ianhuysman]

ianhuysman I agree with Snipergod87's assessment. For my own curiosity, what model of Dell computer did this PSU come in?

It's an older Dell Precison T7400, It's an old computer I know but with 2 xeon X5482's, 16GB ram and a few other upgrades it's a decent computer. But I'm planning to upgrade later this year for obvious reasons.

Can you elaborate on what you mean when you say your system crashes? That can be interpreted in many ways.

I've done some research as to why it crashes, and I found out it could be a power issue. Also it's not a BSOD, the screen just goes black/gray and the system restarts.

 

[photonboy]

Hi,
*It's not a LACK of power though it could be a BAD power supply. One rail does not limit you to that amount per cable. Not how rails work.

You'll want a quality 550W (or so) power supply. There are 450W PSU's that work just fine that have 2x(6+2)-pin connectors. See PCPARTPICKER.

Examples:
https://pcpartpicker.com/product/kz7CmG/evga-power-supply-210gq0650
or
https://pcpartpicker.com/product/DbqdnQ/corsair-power-supply-cs550m
or
https://pcpartpicker.com/product/FQ648d/corsair-power-supply-cp9020101na

Yes, that 450W PSU is just fine though I'd recommend to spend a bit more and think of the PSU as an investment if you plan to build a FUTURE PC (maybe a 650W EVGA G3 or similar).

*BTW, worst-case for a GTX770 is probably about 240W (overclock) which is 20Amps, though you're most likely under 18A.

Graphics cards always use the 12V rail/rails so Amperage is always calculate like THIS:

Amp = Watts/Volts

i.e. 240W/12V = 20A

(just FYI, but some people calculate Watts from the wall, and others just from the power supply. It can make a difference though not in THIS case. A card may draw 150W itself, but you'd see more from the wall as the PSU is maybe 80% efficient so 20% is dissipated as heat)

 

[photonboy]

42Amps?
I suspect that's an estimate of TOTAL POWER for the system as that's about 500W.

Depending on CPU you likely draw about 300 to 350W when gaming in total. A quality 450W PSU can handle that, though again I tend to recommend higher quality PSU's.

 

[ianhuysman]

Hi,
*It's not a LACK of power though it could be a BAD power supply. One rail does not limit you to that amount per cable. Not how rails work.

You'll want a quality 550W (or so) power supply. There are 450W PSU's that work just fine that have 2x(6+2)-pin connectors. See PCPARTPICKER.

Examples:
https://pcpartpicker.com/product/kz7CmG/evga-power-supply-210gq0650
or
https://pcpartpicker.com/product/DbqdnQ/corsair-power-supply-cs550m
or
https://pcpartpicker.com/product/FQ648d/corsair-power-supply-cp9020101na

Yes, that 450W PSU is just fine though I'd recommend to spend a bit more and think of the PSU as an investment if you plan to build a FUTURE PC (maybe a 650W EVGA G3 or similar).

*BTW, worst-case for a GTX770 is probably about 240W (overclock) which is 20Amps.

Graphics cards always use the 12V rail/rails so Amperage is always calculate like THIS:

Amp = Watts/Volts

i.e. 240W/12V = 20A

How could the PSU be bad? It has an 80plus rating and it's a server quality PSU from Dell. Or is it just to old? I could check the inside for blown caps but I don't think there are any because if there were it wouldn't work at all

 

[photonboy]

How can PSU be bad?

No way to know that's obvious other than SWAPPING to a different power supply. Same goes for the graphics card. Most "troubleshooting" of desktop PC's is deciding what to swap.

You'd not see anything obvious likely since the computer starts up and doesn't fail until load. There are numerous small components that could be failing.

 

[ianhuysman]

The problem is I would have to buy at least an 800W power supply and it might nog even fit because it's Dell. Also I would need a PSU with a 20pin cpu power connector. So the only way I can test it is with the exact same PSU, wich would be a waste of money. But I guess I'll first start a new thread about my system crashing before I buy any new parts.

 

[turkey3_scratch]

You would not need an 800W power supply with a GTX 770. I am unsure where you heard that.

 

[ianhuysman]

You would not need an 800W power supply with a GTX 770. I am unsure where you heard that.

I have 2 xeon X5482's wich are 150W EACH, a 770 is about 300W and I also have 2 giant fans (+-250mm) and a lot of expansion cards. At idle my system is pulling 200W and when I do a stress test (GPU and CPU) it goes up to 730W. There's a reason why the built in PSU is 1kW

 

[ianhuysman]

Just a small update: I just ran FurMark for about 20min, without the system crashing and tempratures were stable (73°C), but once I exitet furmark my system crahsed!? I don't know why it would crash as the power usage went down, so I guess it's not really a PSU issue.

 

[turkey3_scratch]

Sudden changes in load like that will usually cause a voltage spike.

 

[Karadjgne]

Cpu crash is a blue screen. Gpu crash is a black screen generally.

Most modern psus have a 20+4 mains connector, so yes, your 20pin is covered, you'd just not use the +4pin.

Unlike most decent units, that psu actually has 5 separate rails, they don't actually come to a single shared output. So it's 18A separate, mains, molex, pcie, molex, molex usually.

I'd start in Windows event viewer. Look up any critical errors. They'll be logged by windows automatically in the event of sudden shutdown.

 

[ianhuysman]

Cpu crash is a blue screen. Gpu crash is a black screen generally.

Most modern psus have a 20+4 mains connector, so yes, your 20pin is covered, you'd just not use the +4pin.

Unlike most decent units, that psu actually has 5 separate rails, they don't actually come to a single shared output. So it's 18A separate, mains, molex, pcie, molex, molex usually.

I'd start in Windows event viewer. Look up any critical errors. They'll be logged by windows automatically in the event of sudden shutdown.

By 20pin connector I mean a 20pin CPU connector, I have a 24pin ATX connector and a 20pin CPU connector.
And I'm already using 2 seprate +12V rails. And I looked in windows event viewer but I didn't find any errors when the system crashed. And here is the link to all the details of the PSU connectors if that might come in usefull: http://downloads.dell.com/manuals/all-products/esuprt_desktop/esuprt_dell_precision_workstation/precision-t7400_user%27s%20guide_en-us.pdf
It starts at page 160, and I'm using P5 and P24 for my GPU.

 

[Karadjgne]

Try p18 & p24. Looks like the pinout is upside down on p5, the hots should be opposite the clip, look like the 8pin with grounds across the top. If that's the case, hopefully you haven't killed the card.

 

[lakimens]

Seriously, what is that PSU with 5 12v rails..

 

[jonnyguru]

It's a Chicony (HiPro) and it's a good PSU. They split up the +12V as much as they can for liability reasons.

Problem isn't not enough power. If you were exceeding the PSU's capability on any +12V rail, the PSU would shut down. You're saying the PSU is rebooting. So it has nothing to do with the amount of power available on the +12V.

 

[lakimens]

It's a Chicony (HiPro) and it's a good PSU. They split up the +12V as much as they can for liability reasons.

Problem isn't not enough power. If you were exceeding the PSU's capability on any +12V rail, the PSU would shut down. You're saying the PSU is rebooting. So it has nothing to do with the amount of power available on the +12V.

I'd listen to this guy, seems like the real jonny

 

[turkey3_scratch]

Seriously, what is that PSU with 5 12v rails..

I don't know if you are implying that having multiple rails is an inherently bad feature of a power supply, but if you are, then you are misled. Done properly, multirail is better than single rail because it offers enhanced protections over single rail. That's all it is: better protections by having multiple overcurrent protection on the 12V rail for designated cables rather than relying on overpower protection for all combined cables.

 

[lakimens]

Seriously, what is that PSU with 5 12v rails..

I don't know if you are implying that having multiple rails is an inherently bad feature of a power supply, but if you are, then you are misled. Done properly, multirail is better than single rail because it offers enhanced protections over single rail. That's all it is: better protections by having multiple overcurrent protection on the 12V rail for designated cables rather than relying on overpower protection for all combined cables.

I'm not implying it's bad, but it is the first one I've seen with five 12v rails. I've seen double and even triple, but this I have not.

 

[turkey3_scratch]

Seriously, what is that PSU with 5 12v rails..

I don't know if you are implying that having multiple rails is an inherently bad feature of a power supply, but if you are, then you are misled. Done properly, multirail is better than single rail because it offers enhanced protections over single rail. That's all it is: better protections by having multiple overcurrent protection on the 12V rail for designated cables rather than relying on overpower protection for all combined cables.

I'm not implying it's bad, but it is the first one I've seen with five 12v rails. I've seen double and even triple, but this I have not.

Aah okay. Confusion cleared.

@jonnyguru: If OCP or OPP would completely shut off the power supply (rather than rebooting), can the same be said for UVP and OVP, or would those protections act differently if they were to kick in, as in a reboot vs a shutdown?