Yo Motherboard

Will My PSU Handle Two 5090s Power Limit at 400W Each?

November 18, 2025 3 answers
Asked by CircuitScribe99
I'm putting together a new build and I already have two RTX 5090s along with RAM and an SSD. My main concern is whether my PSU, the Corsair AX1600i, will be sufficient to power everything. I've set the power limit for both 5090s at 400W each, although from my experience with the current 5950X setup, I know these cards can occasionally draw more than 400W even when limited. In the future, I might add another 96GB of RAM if prices drop, which could require a stronger PSU. Here's what I've noted from my estimated wattage calculations: - AMD Ryzen 9 9950X3D: 21W - 170W - CPU Cooler: 5W - 10W - Motherboard: 17W - 70W - RAM: 94W - Western Digital NVME SSD: 2W - 10W - Each RTX 5090: 143W - 575W Total estimated wattage is around 1554W. Will the Corsair AX1600i be enough?
Corsair AX1600i Hardware hardware PC build power limit PSU RTX 5090

Answers

TechieTinker
Honestly, you've spent a lot on those GPUs, so it might be wise to invest an extra $800 on a more robust PSU. It can help ensure that you don’t run into issues when the power limits are tested. Also, there are external power supplies available that can support one of the 5090s if you find yourself nearing the 1600W limit. It’s a good idea to consider the electrical setup in your space too, as higher power draws may require beefier circuits.

SparkyGadget: I completely agree. Better safe than sorry, right?

GigaNomad: For sure! The last thing you want is for your system to have power limitations when you're using both cards.

Reply to this answer
Readytoplay
Your total estimated wattage of 1554W is within the 1600W PSU limit, but it depends on your usage. Are you planning to max out every component constantly? If you're using the 5090s for machine learning, they might indeed draw 400W consistently during those tasks, so keep that in mind.

OP_PowerUser: Not all the time, but during ML training sessions, yes.

Reply to this answer
WattSavvy
I’m a bit skeptical about that RAM power draw of 94W; that doesn’t seem accurate. If you're mainly limiting the GPUs to 400W, then you should generally stay below 1200W, but it could spike higher. Also, remember that PSUs can degrade over time, so it’s worth considering how old your AX1600i is. If it’s been in use for several years, maybe look into a newer model.

OP_PowerUser: Thanks for the heads up! The AX1600i is still in use with my 5950X, so it should be okay for now.

Reply to this answer

Add your answer

Answers are reviewed before publication.

Related Discussions