Two PSU on one system.

[Coma]

Hi,

Since low wattage PSU cost per watt is way lower at similar quality, I was wondering if I can use a 350W PSU for the motherboard and a 600W PSU to 3 ati 5830.
Is this possible? What are the risks? Did somebody already did this? My idea is to have a more versatile configuration at the lowest cost possible.

[Coma]

You could, but I'd probably sell both PSUs and buy one reasonable one.

The problem is that the difference in price is huge on most cases.

I didn't do it yet, but it sounds interesting. You'd need sort of a dummy plug to get the GPUPSU going though, because the mainboard normally tells the PSU when to start. Also, find out about the rails on that 600W PSU, it's quite possible that they are distributed in such a way that you simply can't power three cards at once.

Yes, maybe some jumping of ATX conector on the GPU PSU is required. The rails problem I don't think would be a problem since most cards comes with Molex to PCIE power adaptors.

[Coma]

Yes, maybe some jumping of ATX conector on the GPU PSU is required. The rails problem I don't think would be a problem since most cards comes with Molex to PCIE power adaptors.

Yeah, mine too, but my molex rails were 240W, that's just enough, and I had a 1000W PSU. Might be worth checking

Will do if I can figure out a way to set this up.
Thank you.

[DanielC]

http://blog.zorinaq.com/?e=42

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[Coma]

http://blog.zorinaq.com/?e=42

Scroll down.

That's awesome. Very informative. Apparently it is more or leass easy, but in that case I have only one doubt.
How does it turns on?

Then I wonder: what might happens if the motherboard is turned on and the graphic cards PSU is still shut down?
And viceversa?
What would be the best way to power up a rig like this?

[bcpokey]

The english in this thread is a bit confusing, so I will just make some statements and if they're not totally on topic I apologize.

First, it is very easy to set something like this up, there are even cheap little buttons you can buy for like $5 to basically be an on switch for both PSUs.

Here is one of the eaiest guides I've seen on the subject: http://www.overclock.net/power-supplies/14455-multiple-power-supply-guide.html

Now with that said my suggestion is: Don't do this. It can have some problems which are obvious and ones which aren't so obvious (like imbalanced grounding). This is just a suggestion of course.

I am running 2 5870s and a 5850 on a single x650, and my power meter reads off their consumption for the entire system at 550W. I don't suppose 3 5830s uses more power than that, so I would be comfortable in recommending a 650Watt power supply as enough for 3 5830s (assuming you downclock the memory and use an efficient and small CPU like me, I am using a 45W sempron). An antec Earthwatts 650 can be had for $65 last I checked. That's pretty reasonable for a good PSU.

[Convery]

http://blog.zorinaq.com/?e=42

Scroll down.

That's awesome. Very informative. Apparently it is more or leass easy, but in that case I have only one doubt.
How does it turns on?

Then I wonder: what might happens if the motherboard is turned on and the graphic cards PSU is still shut down?
And viceversa?
What would be the best way to power up a rig like this?

When I installed a second PSU I just faced a single problem.. When the computer was turned off the GPU fan went at full speed as it got power but no instructions.

That could be fixed by linking the PSUs together though or having a mosfet-like switch..

[interwho]

I'm doing this on my miner. One 300W to the mobo, one 250W to a single 5850, in an old HP a6000n mini-tower. The 300W is internal, the 250W is located outside the case with a bit of wire on the mobo connector (green wire to black) to trick the psu into staying on. It works, although I'd set your computer BIOS to automatically restart if there is ever a power outage, and make sure to turn on both PSUs at the same time.