The most accurate method is to read the sticker located directly on the power supply unit. Reddit·r/buildapc
But there’s a problem:
The most reliable way to identify your PSU wattage is to physically look at the unit itself. Software can be wrong, but the label on the metal chassis is the definitive source. check pc power supply wattage
If you can’t (or don’t want to) open your case, you can’t read the wattage directly. But you can estimate your needs and work backward. The most accurate method is to read the
Take ten minutes this weekend. Open your case. Read the label. Or run a calculator. Because when it comes to your PC, a strong heart is everything. A weak one is just a crash waiting to happen. If you can’t (or don’t want to) open
A generic "500W" PSU from a budget manufacturer often cannot actually deliver 500W continuously.