GPU rig with dual PSUs.. how many watts each??

[couture]

Im building a gpu rig and am thinking of using two psu's.. one to send power just to the gpus via the 6pin PCIe plugs and the other smaller psu to send power to the motherboard

Im wondering how many watts each needs to be

Assume MSI Z97 Gaming 7 mobo with usual ram, cpu and ssd with 6no. powered USB 1x to 16x risers to 6no. sapphire rx470s


Will the gpus draw as much power as they can through the risers and therefore the mobo if no other cables are plugged directly into them? (6pin pcei)
Will the gpus draw half from each? Mobo and 6pin?
If i am powering the gpus via a second psu do i even need powered risers?


Just trying to work out how many watts each psu needs to be before purchase

Thanks all in advance

[Celsiuss]

Why do you want two PSUs? One should be enough for 4 or less GPUs. How many GPUs do you want?

According to this your GPU wlll use at most 140 watts. f you have 4 of these, I'd recommend one PSU of 1000 watts.

For the love of god, connect the PCIe power cables! The GPU can barely draw much power from the PCIe slot itself, and most likely will not work. The GPUs get most of their power from the PCIe (6pin) cables, they don't draw much from the motherboard.

Also for your 24/7 (im assuming) mining rig, dont cheap out on the PSU, don't get an unbranded grey PSU made in China, get a decent one!

[Vaccinus]

i think you never need two psu, most of the time a 1200 from corsair or a evga 1300 will do it, because right now the gpu are very efffcient, and next egneration will be more efficient, i'm using a 1000 watt and run 6 card without problem, just below 80% tdp

[Jdope]

I don't think one to power the mobo and the others is realistic, the mono and the processor (specially if you're using a Celeron) takes little wattage compared to the cards, anyway I would advise you to get 2 750w psu, one for the mobo and 3 cards and one for 3-4 cards more!

[couture]

Thanks for the replies everyone

I was planning on using a corsair 350W to run the mobo, cpu, ram, ssd etc
Then use a 1500W server PSU with a custom breakout board to run pcei 6pin power leads to the 6 gpus

Reason for this is to reduce the costs of power supply - 1200W corsair or evga PSUs aren't cheap


So thoughts on the small mobo Corsair working with the server PSU providing the big load for the gpus?

[Vaccinus]

Thanks for the replies everyone

I was planning on using a corsair 350W to run the mobo, cpu, ram, ssd etc
Then use a 1500W server PSU with a custom breakout board to run pcei 6pin power leads to the 6 gpus

Reason for this is to reduce the costs of power supply - 1200W corsair or evga PSUs aren't cheap


So thoughts on the small mobo Corsair working with the server PSU providing the big load for the gpus?

1300 watt evga is very cheap, you can find it for $100 used, and even new is still very cheap not more than $150, i don't like all the trouble with two psu and there are bad story with some incompatibility with asrock h81 and the two molex

[dragonmike]

There's no trouble with two PSUs, just use a connector and you're good to go. A decent (semi/)modular 750W PSU will have 4 PCI-E cables and connectors too so you won't have to worry about having enough of those if you plan to run a 7-GPU rig for example.

[couture]

If I can find an evga for a good enough price then I'll grab one of those

Otherwise... I'm guessing a 1500W server PSU with custom breakout board (other benefit is no gpu daisy chaining required.. just run enough 6pin PCIe cables from the power rails on the PSU) with a 350W PSU for the mobo would be enough?

That's more than enough power directly to the gpus - plus surely enough power to the mobo?


I'm guessing server PSUs have some benefit as many people with large mines use them?

I'll keep my eyes peeled for evga though


P.s has anyone used the msi gaming 7 mobo? I know people have used the msi gaming 5... but not heard much about the 7?

Thanks!

[newmz]

I'm running an Nvidia rig on an Asrock H81 Pro BTC. 2 x gtx 1070 and 2 x gtx 1060.

One single Corsair RM850x is plenty for the whole thing - motherboard, CPU, SSD, and all 4 GPUs. All GPUs running overclocked at ETH uses around 600W, Equihash (ZEC, ZCL, HUSH) uses around 500W.

I know very little about the newer RX AMD GPUs because I think Nvidia (although expensive) GPUs are superior in almost every way. Same hash-rate as my older R9 290 based rig, at half the power.

If you can get a PSU with enough wattage and enough PCIe outputs - just use one. So much easier.

My AMD rig (3 x R9 290, 2 x R9 290x 1 x R9 390) uses 2 x 750W PSUs but if I was starting out now (with AMD RX GPUs) I would definitely just use a single PSU.

[JaredKaragen]

Ill agree;  one PSU is less fuss than a multiple PSU setup.  Less mass, less weight, etc.

But;
For the MB, you could get away with an old "retail pc" PS of like 200-250W; then just use a second PSU that has enough +12V amperage to supplement the GPU's risers and fans separate.  Just be sure the second PSU has a switch-on time equal or less than the main motherboard PSU or issues will arise.

Using newer GPU's (average of < 150w each lets say), and staying under 7 GPU;  I don't see why a 1000-1100w PSU wouldn't be more than enough.... and they are ~$100 or less nowadays.    Far from when a 1000w+ PSU was a minimum of a $250 investment...

I got my last Coolmax 1600W PSU that's in my current RackMiner for $100 used.   It's only Silver rated... but it was only $100.   Hands down, better than a 2 PSU config in every way.