2 pcs, one psu.

robinlawrie · 23 Jul 2012 at 09:29

hi. i purchased a thermaltake toughpower 1475w psu. it has 2 huge 12v rails.

i intend to use it to run 2x pcs in one case for a custom workstation/renderbox.

(3930k, rampage gene, 32 gb 1866 ram, corsair h80)

i have all the parts sitting here but got a sudden attack of "i dont want to break all this expensive stuff"

i have created a custom splitter for the 24 pin motherboard connector, but i will swap the +12v pins in the second connector to the second 12v rail on the psu, so i dont overload one 12v rail.

my question is, do the seperate rails have seperate ground connections or are they all common? im assuming its a common ground throughout.

second, do you see any other issues with this setup? one question is if i wanted to switch on the pc's independently, so i can leave the second off when not rendering, to save power, is it ok to have the psu powered up, but the second connected motherboard not switched on? or will this likely fry something?

many thanks guys..

tamzzy · 23 Jul 2012 at 09:31

blimey why dont just buy 2 standard psu lol
nah i wouldnt have a clue how splitting a psu would work lol

robinlawrie · 23 Jul 2012 at 09:36

if i bought 2 standard psus it wouldnt all fit in one midi tower case... its an experiment in fitting stuff in a small box.

-and yes, i know, an sr-2 was an option too, but the sandy bridge-e chips give a decent boost in my software, and the SB xeons are not overclockable. bang for buck wise, a pair of pcs with 3930's is the winner. however i decided to fit them in one box. it all fits.. airflow seems good, i just want to check the wiring before connecting the second board up.

Tealc · 23 Jul 2012 at 10:24

It's all a common ground. It's usually all a common 12v as well, it's just current limited by the PSU into 'rails'.

I'm not quite sure what'll happen to one PC#1 if you power up PC#2. As far as I know it's just the short across Green and Ground that causes the PSU to just power whatever it's connected to, so both PC#1 and PC#2 would start up.

If this is the case then I'm not quite sure how you could switch all the wires going to one PC and all the wires going to the other PC at will without having to flip a whole load of high current switches.

Hmm.Edit: Did a little research and it might be possible..

Here is the power up sequence.

1. Turn on PSU
2. Power up "Main" mobo using the power switch. The fans for both mobo's should kick on, but only the Main mobo will boot.
3. Once the Main mobo has booted, hit the power switch on the secondary mobo, it should start to boot. You may need to hit power on the secondary mobo a second time if the first hit does nothing.
4. Once both mobo's are booted up successfully, I like do it again and check the voltages in the BIOS, I suggest you do the same.

Saw it here

So having one rig's fans running can easily be sorted, perhaps even as simply as having them connected to the motherboard and at worst having them run through a latching switch.

robinlawrie · 23 Jul 2012 at 13:07

nice one.. just what i was looking for.