Multi-rail PSU? how to properly setup

[jose4cc]

Hi,

I have a mini-rig for experiements.

Two GPUs (RX570) with a small motherboard (Gigabyte H110M-A) and risers.

I have these risers: https://www.amazon.ca/gp/product/B076KLJR2Y/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1.

My PSU is a Corsair 850i. It comes setup for multi-rail operation by default (it can be changed to single rail).

So, how should I connect this (power)? more importantly, how should I  NOT connect this? (ie: what would be unsafe/wrong).

My plan is to use using PCIe cable and plug the two risers in it (use the 6 PIN power plug in the risers), and use individual PCIe cables for each video card. Is there a way to test the risers before actually plugging the video cards in them?

My understanding is that that should be safe (all power is coming from the same PSU, even though they are different rails).

Please advise. Thanks.

[1715201818]

1715201818

[1715201818]

1715201818

[1715201818]

1715201818

[steve666]

It's simple as... you know what... Just connect one rail to one GPU and thats it. It also depends on how much power can be drawn from one 12V rail, for example if your multi-rail PSU has 20 amps per rail at 12V it may deliver 12*20 = ~240 Watts of power.

[Vann]

According to the PCI-E spec, you need to make sure that the 6/8 pin connectors on the VGA supplemental power of the card come from the same rail on the PSU.

[jose4cc]

It's simple as... you know what... Just connect one rail to one GPU and thats it. It also depends on how much power can be drawn from one 12V rail, for example if your multi-rail PSU has 20 amps per rail at 12V it may deliver 12*20 = ~240 Watts of power.

So... do I connect one rail (cable from PSU) to each riser/video card combination?

[steve666]

Exactly GPU and its riser should be connected to one 12V rail for the best performance and to avoid potential mismatching (which actually shouldn't matter that much as long as these PSU are build for applications like that)