Add up your components to size a power supply, with headroom for GPU transient spikes.
How the psu calculator works
Component power draw is the easy part. The catch is transient spikes: modern graphics cards can briefly pull far more than their rated board power, and a supply sized only to the steady-state total can trip its protection and shut the system down under load.
The recommendation here builds in that spike headroom, then rounds up to a standard size. The sweet spot figure is higher again — running a supply at about half its rating is where efficiency peaks and the fan stays quiet.
How to fill it in
- Enter your CPU TDP and GPU board power from the manufacturer specs.
- Add drives, RAM sticks, fans and cooling.
- Set an overclocking allowance if you run one.
How the number is calculated
Try it with these numbers
On the values this calculator opens with, the recommended PSU is 750 W. Underneath, CPU + GPU comes out at 410 W and Everything else at 82 W. Change any field and every figure updates as you type.