Server PSU on Biostar MOBO, need help!

[philippew]

Hi everyone!

I'm having some trouble setting up my rig:

-simpleminingOS
- Biostar BTC 250 PRO mobo
- 12 1080ti
- 850w atx psu
- 2 2400w server psu (http://www.parallelminer.com/product/2400-watt-power-supply-kit-for-gpu-mining-94-efficiency-200-240v-up-to-24-gpu/)

I have 6 GPUs on one psu and 6 on the other
850w is powering the mobo and the risers

I was able to get mining for a minute or so and then It crashed, when I tried to turn off the Mobo PSU it wouldn't go off, I pulled the plug and it was still on, somehow beeing powered by the GPUS, how is that possible? Anyway, I think that is the reason it's crashing, can someone help me on that?

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[Apneal]

Its not the reason its crashing. Some of the server PSU power does get drawn thru the card into the board to power things like lights, but it does not affect regular operation while turned on.

[Undefined31415]

Can you be more specific about your 850W PSU?

My first guess would be that the 850W PSU is your problem. I don't think it can power all 12 risers.
Suppose each of your cards draws an average of 75W through the risers themselves. (I'm guessing here, since I can't get a better estimate without knowing more about your specific 1080ti cards. Even if I knew which type and how many power connectors are used, I can't be 100% sure how the entire power draw of the card is distributed between the PCIe power connectors and the riser card. I'd just have to guess with the assumption that everything is within the power specs of each connection.)

Anyhow, if your 12 cards average 75W through the risers, you reach 900W (plus the motherboard/CPU/etc.), which pushes your 850W PSU beyond its rating. Even for a high-quality PSU, that's not going to work for 24/7 operation.

Some people recommend powering each riser from the same PSU that powers the card connected to that riser. Some say to always power the risers from the motherboard PSU. Others say it doesn't matter. Personally, I haven't had a dual-PSU configuration where it mattered, but my cards are much less power-hungry than the 1080ti cards typically are.

Tl;dr: Have the 2400W PSUs each power some of your risers and take some of the load off of the 850W PSU.


EDIT: After looking closer at the 2400W PSU kits you linked, I hope your powered risers take 6 [or 8] pin PCIe power connectors.

[philippew]

UPDATE:

After doing some troubleshooting I got to the following:

I isolated the troubleshooting to only 6 cards (atx psu + 1 server psu)

When I start all of them it only recognizes 4 of them.

I isolated the first the first 3 and they worked fine, after I tried the last 3 and it worked as well.

But then when I connect all 6 or even 5, they show only 4 running.

I tried variations of sata cables for the risers, using 2 risers per cable, nothing changed.

The conclusion is that all hardware are working....

Any guesses?

[philippew]

Update 2: Iused another atx PSU, and same problems...

[Kronny]

Try to connect risers and gpus at the same PSU.

[philippew]

I found out the problem but still don't have a solution for it: the CMOS failed and reset the bios to the factory default. This happened several times and I believe it has to do with the power from the PSU servers somehow getting to the mobo and faulting the CMOS, since when I disconnect the ATX PSU from the power it still spins and the CPU fan as well...