External PSU for GPUs

[LtStaffel]

Hello all,

 

I recently acquired (they're otw) an EVGA FTW ACX GTX 980 and a reference RX 480 for a total of 315W TDP. I am going to be plugging them into my server using USB to 16x risers which will be plugged into a PCI USB card which is actually plugged into yet another server riser which is finally in the MOBO.

 

Regardless the mess, because it is a PowerEdge, it does not have spare PSU cables that can be routed to the GPUs, plus they will be outside it already. Hence, I am going to use another PSU specifically for them.

 

I've seen it as an idea several times, and believe it is possible, but was wondering if anyone here had input on it and/or has done it before themselves.

 

Thanks in advance!

[RadiatingLight]

should work fine.

just connect the green wire with any black one on the 24-pin on the PSU, and you should be good.

[LtStaffel]

6 minutes ago, RadiatingLight said:

should work fine.

just connect the green wire with any black one on the 24-pin on the PSU, and you should be good.

it'll need to power two cards, do you have a PSU recommendation?

[RadiatingLight]

1 minute ago, LtStaffel said:

it'll need to power two cards, do you have a PSU recommendation?

anything tier 3 or above (PSU tier list in sig) that has enough connectors to power whatever you need, plus maybe a bit extra for any future cards. keep in mind that you can also adapt Molex to a 6-pin, but this will not provide the full 75W of power (more like 60 IIRC), and if you draw 60W from every Molex plug in a chain of 4, the cables will start to get really hot, since the PSU isn't really designed for that much of a load.

 

[LtStaffel]

2 minutes ago, RadiatingLight said:

anything tier 3 or above (PSU tier list in sig) that has enough connectors to power whatever you need, plus maybe a bit extra for any future cards. keep in mind that you can also adapt Molex to a 6-pin, but this will not provide the full 75W of power (more like 60 IIRC), and if you draw 60W from every Molex plug in a chain of 4, the cables will start to get really hot, since the PSU isn't really designed for that much of a load.

 

What exactly do you mean by the PSU isn't really designed for that much of a load?

In looking at my exact cards, (the 480 is actually an XFX), it looks like I'll need 3 6pin connectors (2 for the 980 and 1 for the 480). Then I'll also need to figure out how to power those Molex/SATAs from the risers, which I think is why you mentioned them.

[Stefan Payne]

If that PSU has only a +5VSB Rail and not an 11V Standby Rail, you can use every high quality (DC-DC) unit on the market with an adaptor and don't need two PSU or something like that.

 

And before someone mentions it:
No, he must not use S-ATA to PCIe Adaptors because that kann burn the traces on the board because the PSU only has two connectors going to the Board - no 3,3V and +5V rail whatsoever! All on the Board.