What power supply does the RTX 4090 need?
The RTX 4090 draws 450 W on its own. Here is what that means for the supply you buy, and why the answer is not simply that number.
800 W
For a complete system drawing about 605 W under load.
Where the watts go
| Graphics card | 450 W |
|---|---|
| Processor (mid-range estimate) | 105 W |
| Board, memory and storage | 50 W |
| System under load | 605 W |
The recommendation adds 25% over measured draw. That is not padding: a supply run near its ceiling sits in the least efficient part of its curve, and graphics cards draw in microsecond spikes well above their rated figure.
Check the connector, not just the watts
At this power level the RTX 4090 expects a 12V-2x6 (12VHPWR) connector. A supply with enough watts but only legacy PCIe plugs will need an adapter, and adapters are where most of the reported melting incidents start. Prefer a unit with the cable built in.
Different processor, different answer
This page assumes a mid-range CPU. Pick your own parts and the calculator works the total out for your machine.
Open the calculator