Folding Farm: Do you need a seperate PSU for every mobo?

wussboy · Post by **wussboy** » Fri Jun 13, 2003 9:28 am

Just wondering. Is there some way to use a PSU for more than one board? Even if it wasn't a regular computer PSU? Any thoughts would be appreciated.

miker · Post by **miker** » Fri Jun 13, 2003 9:36 am

No way.

Zhentar · Post by **Zhentar** » Fri Jun 13, 2003 9:39 am

I think that one 300 watt PSU should be able to handle two mobos if you had a Y mobo connector, please tell me if you find one. I think even the 180 watt ones I'm gonna get would do the trick; but again, you'd need a Y connector. The two 180 watt fortons will cost my $40, 1 300 watt would be $27 so there clearly is room here to save money, but I don't think its worth the trouble; I'm just gonna settle on SFF low power PSUs that hopefully are quiet....

dukla2000 · Post by **dukla2000** » Fri Jun 13, 2003 10:23 am

You may be in with a chance but you will need to do some non-standard work.

On the 1 hand get a Y splitter. But you will need to make special provision for the PS-ON and PWR-OK lines (i.e. things may get confused it you double them up/split them. You may need a separate little switch box to manage them - off hand I cant remember the purpose of PWR-OK).

The other problem is you should really ensure the psu VCore source is not split from a single original wire(s). Assuming we are talking Athlons, then most likely the mobo derives VCore from +5V. Rather than splitting the four +5V wires, you should really get 4 new ones from the psu pcb. While you are at it you should probably get fresh COMs from the psu pcb ...

At which stage you get my vote for some cheapo psus

Zhentar · Post by **Zhentar** » Fri Jun 13, 2003 10:43 am

PWR_ON is what the Mobo uses to turn on the PSU, PWR_OK is from the PSU saying the voltages are okay to run, so if any voltage rails get too far off the system can be shut down (such as when I short out the 12v rail......)

I don't think having two mobos there would confuse it, but I don't know.

Like dukla said, I think the best bet is two cheap PSUs, like the 180 watt ones I'm going to get; it may not be the most effecient plan, but it's easier...

Wrah · Post by **Wrah** » Fri Jun 13, 2003 12:56 pm

You may find this link usefull : Two Motherboards, One Power Supply

miker · Post by **miker** » Fri Jun 13, 2003 1:01 pm

Color me corrected.

Zhentar · Post by **Zhentar** » Fri Jun 13, 2003 3:00 pm

not bad; there's just one problem: the three power connectors cost $15; buying one 300 watt versus two 180s is $13.

Also, he's wrong when he states the importance of getting the wires right; just get all the same colors matching and it should work just fine.

dukla2000 · Post by **dukla2000** » Fri Jun 13, 2003 3:50 pm

I guess its a toss up between a dodgy Y-cable and cheapo psus.

I would still feel more comfortable using some extra +5V and COM wires from the psu pcb (re-use from the AUX connector). The ATX spec for the 20 pin connector is 6A per pin. With four +5V that is 120W, and I figure 2 Athlon mobos can get close to that. Then again, with a half decent psu to start with hopefully the first connector in the chain can handle more than 6A per pin?

In fact a better (?) version of that Y-cable would be to trash BOTH female plugs from the new extensions, as well as the male from the psu, and solder it all directly thus eliminating resistance inherant in the plug pin connections.

wussboy · Post by **wussboy** » Sat Jun 14, 2003 11:56 am

Thanks guys. Good links and good advice. I've been thinking about starting a little farm. Gimme a couple months, though.