PSU question for dual 3090
Posted by Timziito@reddit | LocalLLaMA | View on Reddit | 10 comments
Hello my humans! I am having having a hard time picking PSU for my dual 3090 what are you guys using?
Best regards Tim
Threatening-Silence-@reddit
Corsair 1000w and addpsu with a 650w, so two PSUs, but I'm going to move up to a single Corsair 1550w for simplicity.
Timziito@reddit (OP)
Sounds like a plan, will aim for that aswell then.
Ok_Mine189@reddit
1500W PSU is an overkill for 2x3090. Don't buy it unless you're certain you'll be adding more GPU in the future. A good 1000W PSU will easily suffice.
FYI I'm currently running 4070 Ti Super + 3090 + 2x3060 and the power draw of the whole system tops at around \~700W at the socket when inferencing (this includes my display).
My PSU is Be Quiet Straight Power 12 1200W.
Timziito@reddit (OP)
Ok! But do you undervolt or anything like that? I have 12 drives attached but it would likely not do much diffrence.
Ok_Mine189@reddit
I limited the 3090's TDP to 80%, others are running stock. I guess I could limit them too for even lower power consumption.
AD7GD@reddit
The issue is running out of PCIe power connectors on the PSU side. I have a few different wattages of Corsair PSUs that have 6 of those connections on the PSU (includes the 1000W). If your mobo needs 2 (depends on the motherboard), and you need 2 each for GPUs, that's just enough. If one GPU is a 3090ti or higher (needs 3x connections at the PSU) you're going to run out.
This is why I just got one of the Corsair "shift" powersupplies. They seem to put more connectors on the side. The 1000W "shift" has 7 PCIe power connectors and the 1200W has 8, which is enough for 2x to mobo and 3x to each of 2 GPUs.
BTW you can use 2 PSUs just fine. You can get a cheap little board that you plug the second PSU into that makes it turn on with the first. They made a zillion of those for crypto mining. If you already have a spare PSU, that will be the cheapest (if not pretty) way.
Timziito@reddit (OP)
I'm going to have two 3x8pin gpus and a bunch of drives around 12. maybe 1000w will do just fine.
No-Statement-0001@reddit
I run mine with a 1000w PSU, it’s fine. 3090 over 300W has diminishing returns on tok/sec.
Get a good quality/brand power supply though. I have an evga and it’s been solid.
Timziito@reddit (OP)
Thanks! And thanks for the 300w heads up, will look into underwolting then.
a_beautiful_rhind@reddit
Just turn off turbo.