Custom PSU for Server mother Board

[pringleman]

I am building a render farm using the following Motherboard - - SuperMirco X8DTT
See original thread - http://www.tomshardware.co.uk/answers/id-2797212/xeon-x5650-cluster-build-renderfarming.html


Well all the components have come minus the case and the biggest hurdle is getting the PSU 20 pin connector correctly working with Supermicro's custom layout




There are hardly any threads/info on this so I thought a fresh one would do for clarity purposes.

Now I have this 450 watt delta PSU and a 24 to 20 pin adapter with a plan to re solder the pins correctly-

Now before I start there are few things I'm still not understanding and would like to check with some experts if my wiring diagram is correct.

It basically seems that the supermicro standard is less complex than the desktop standard 24pin arrangement. but I'm thinking its too simple. Most of the layout seems comprised of just ground and 12V+ lines



Link to PSU - http://www.thirty-day.com/product/delta-450w-active-pfc-intel-xeon-server-dual-rail-12v-atx-248-pin-power-supply

Link to Motherboard - http://www.supermicro.co.uk/products/motherboard/QPI/5500/X8DTT-F.cfm

 

[Eximo]

I suppose I don't actually see a question here. More a list of thoughts?

Most computers run on 12V these days so you really don't need a lot of wires to carry 5V, 5V Standby, 3.3. The current/wattage required is minimal from those sources.

They still have all the voltages there, including -12V, so it really isn't that different.

 

[makkem]

Hi
Some power supplies have a minimum load requirement for the 3.3V and most require a minimum load on the 5V lines neither of which appear to be connected.
If the pinout diagram is correct then the way you are proposing to wire it looks to be ok.

 

[Eximo]

I think I may have read that chart backwards. I was comparing the two if they used the same symbols.

Any recent PFC power supply should be okay to start without minimum loads. Look for supplies labeled "Haswell Ready"

 

[pringleman]

I suppose I don't actually see a question here. More a list of thoughts?

Most computers run on 12V these days so you really don't need a lot of wires to carry 5V, 5V Standby, 3.3. The current/wattage required is minimal from those sources.

They still have all the voltages there, including -12V, so it really isn't that different.

My question is clarification for the new power pin layout I'm proposing, I am a novice but understand the basics of electronics, I don't particularly want to test my theory out on the hardware with out being confirmed by someone with knowledge.

I'm also trying to leave behind a solution in case someone else needs this knowledge as i said there literally nothing on the web detailing using normal PSU for server hardware.

 

[thx1138v2]

Yes, there is more to the power than just the Wattage rating. PSU's have multiple 12V "rails". A "rail" is a circuit in the PSU that supplies a given amperage at a given voltage. So a PSU can have multiple 12V rails that run independently. On the mobo a given rail goes to a given section on the mobo. It gets a bit more complicated because rails with the same voltage can have the amperage split such that you can have something similar to this

Rail A: 12V at 15 amps
Rail A: 12V at 15 amps
12V not to exceed 25 amps

So although each rail could deliver 15 amps by itself, combined they can only deliver 25 amps. This is just an example.

Which PSU rail is delivered to what components on the mobo is determined by the pin layout of the cable and the circuits attached to the socket on the mobo.

So what you need is both a schematic of the PSU outputs and the mobo circuits to know what to connect where which will determine which 12V wires you put where in the PSU cable header and what they connect to on the mobo.

If the mobo manufacturer has a PSU for this mobo, get it. You may or may not find the schematics you need and trial and error may damage either the mobo and/or the PSU.

Here's a link with more info on PSU configurations:
PSU 101

 

[Eximo]

Or use a alternative like this:

http://www.ebay.com/itm/Vicor-MegaPAC-MP6-77518-DC-Power-Supply-2-1-12V-8-3-40A-/201440697080?hash=item2ee6cd1af8

You can get different Vicor modules (DC-DC converters) and get whatever voltages you need.

 

[pringleman]

ok, well it's amazing what results searching google on another day can bring you-

http://www.jonnyguru.com/forums/showthread.php?t=12212
https://rochegregory.wordpress.com/2015/03/10/132/
https://rochegregory.wordpress.com/2015/03/14/supermicro-x8dtt-hef-mod-a-power-supply/

I have found these examples of people trying to do the same. Rounding up everyone's knowledge it seems to be that having enough amperage for the nodes and having it spread across the correct rails so it's evenly distributed is the main problem to solve.

I have now just realized that the PSU's I bought might not be powerful enough, their combined rails output is 33 amps, one rail is 15 amps the other 18 amps, they just meet the lowest rated spec of of the original chassis PSU which is rated at 65amps. With the PSU above the lowest version chassis you can buy being the 980 watts version @81amps.

I have 2 450watts PSUs so assuming that the amount of amps is split among each dual CPU motherboard evenly, each one will take 32.5 amps which my Delta PSU just makes but I am mainly wondering shall I send these back and get a batter PSU from Delta... The 600 watt version with a 42amp output maybe?


I should say now that my build is not going to be as power intensive as a server machine as iI will only be using MAX 2 HD's and the CPU/ram included.


I also found this but to use it doesn't make much sense without the rest- http://www.ebay.co.uk/itm/Supermicro-1U-SC808-Power-Distributor-PDB-PT808-S20-Rev-1-0-last-one-available-/281810452617?hash=item419d364089


Does any one think I'd be safe to keep the 450watts PSU as combined they do meet the 780watt Chassis spec for the motherboard I have? If I open them up even to inspect I won't be able to send them back.


Power supply links -

Supermicro Redundant Power Supply PWS-981-1s - http://www.useditoutlet.co.uk/new-supermicro-redundant-power-supply-pws-981-1s-259-p.asp
http://www.ebay.co.uk/itm/USED-Supermicro-PWS-781-1S-780W-1U-Power-switching-module-Cold-swap-Power-supply-/301479409224?hash=item463192b648&autorefresh=true


Chassis link - http://www.supermicro.com/manuals/chassis/1U/SC808.pdf

thanks all!

 

[Bintzu]

Did you have any luck getting this to work? I came across one of these motherboards for next to nothing, I might try pulling 12v lines from the esp connector and pci-e connector for a balanced load

 

[pringleman]

still working on a solution hopefully will have some progress this week but i have bought the official PSU and bridge connector to see if this will work for me. So far what I did, did not work.

 

[Celdwist]

still working on a solution hopefully will have some progress this week but i have bought the official PSU and bridge connector to see if this will work for me. So far what I did, did not work.

I have the same problem too! Wouldn't 2 psus work? Like both having the 12 pin to 10 adapter? And plugging them in each motherboard connecter?