Hi all,
I have a GPU rig that isnt quite booting correctly and am wondering if someone might notice something obvious im doing wrong...
Rig:
Mobo - Asrock H81 Pro BTC
CPU - Intel Celeron usual thing
Ram - 4GB HyperFury
SSD - 32GB USB
OS - EthOS
PSU - (PSU1 EVGA 650 GS) and (PSU2 EVGA 650 G2)
Risers - Usual 1x-16x powered
GPU - 4no. Sapphire RX470 OC Reference
(PSU1 is always powering the mobo)
I can get the rig to boot with 1no. GPU plugged into PSU 1 (both riser power and card power) and with 2no. GPU plugged into PSU 1 (both riser power and card power).
If I plug more than two GPUs in, then the PSU clicks (presumably an overcurrent protection of some kind) and the rig wont boot.
(I can repeat this two gpu set up with PSU2 as well as proof that the second PSU is working)
I then try to power the other two cards with the second PSU..
I have tried booting with PSU1 taking the mobo and 2no. GPUs (riser and card power) and with PSU2 taking 2no. GPUs (riser and card power) I then bridge the pins on the 24pin connector of PSU2 and power it on just before powering on PSU1 (i have also tried powering it on just after powering on PSU1 to the same effect)
This either doesnt boot anything at all and both the PSUs click (the presumed overcurrent protect?) Or PSU1 boots and PSU2 stays off...
I then tried plugging all four GPU riser card powers into PSU1 (along with the mobo) and the card main power into PSU2 but this does the same PSU click and nothing...
In my process of debugging.. I also discovered that plugging PSU1 with the mobo and 2no. GPUs would only boot when the riser board power cable adapters were plugged in???
So the riser boards have molex plugs and then molex-to-sata adapters... the rig will boot IF the molex-to-sata adapters are plugged inbetween the riser board and the PSU, but if i remove the adapters and just plug the riser boards in directly to molex cables from the PSU then i get the same PSU click and no-start..
Please see this image for clarity
https://pbs.twimg.com/media/DGp9vOHWAAAwqHA.jpgBlue lines are power lines to the PCIe riser boards and pink lines are main power to the GPUs
Is option A or B correct? Or is there another option..?
Oo... furthermore, I tried to plug in some Sapphire Nitro+ RX570 4GB cards that I have on another rig and they work just fine, except when I try to run one RX570 and one RX470.. in which case it doesnt boot...
I hope this all makes some semblance of sense.. I have been trying a million different wiring configurations and spend hours plugging and unplugging to no avail!
What am i missing! haha
Much appreciated