Sheet 04 · Power budget
Size the supply.
Type in the sustained watts for each part, choose how much headroom you want, and read off a suggested power supply rating rounded up to the next 50 W. The numbers are yours; the sheet just adds them honestly.
- Sheet
- 04 / 06
- Input
- Watts, %
- Output
- PSU rating, W
- Rounding
- Next 50 W
Component ledger
Watts, sustainedMargins
Headroom is spare capacity above your sustained draw. Efficiency is only used for the wall-draw estimate; use the figure from your supply's data sheet at your expected load.
Where the watts go
Each patterned block matches the swatch beside a component. Exact shares are in the ledger.
Suggested supply capacity
Load Headroom Spare from rounding
How to use it, and where it stops
Entering watts
Use the rated or measured sustained draw for each part, from its own data sheet. Start with the processor and graphics card, which dominate the total, then add the board, memory, drives, fans and anything powered over USB. Use Add a part for anything else, such as a capture card or extra fans.
A blank row counts as zero. A row with a negative, non-numeric or absurdly large value is flagged, and the totals pause until it is fixed so a typo never turns into a wrong recommendation.
Headroom
Headroom keeps the supply away from its limit so it runs cooler and quieter, and leaves room for short spikes and for upgrades. There is no single right percentage. A higher number is safer and costs size; a lower number is only reasonable when your figures are measured rather than assumed.
Rounding
The minimum is your total plus headroom. The suggestion is that minimum rounded up to the next 50 W. The capacity bar shows how much of the final rating is load, headroom and rounding.
Edge cases
Graphics cards can briefly draw more than their sustained rating, so lean toward more headroom if your card's maker mentions transient spikes. Overclocking raises both processor and card draw. Wall draw is the DC load divided by efficiency, so it is higher than the load; efficiency changes with load, which this sheet does not model.
Small form factors cap out at a modest wattage compared with ATX. If the suggestion is larger than the supply you can fit, check Clearance for the form factor and then reconsider the parts, not the headroom.