Look for the number. That is the power the CPU and GPU actually use. If a PSU says 600W total but only provides 300W on the +12V rail, throw it away. Stick to brands like Corsair, EVGA, Seasonic, and be quiet! The Bottom Line Calculate your wattage before you buy the power supply.
Your PC will run quieter, crash less, and be ready for future upgrades. And honestly? Sleeping well knowing your house isn't going to trip a breaker is worth the extra $20.
Use the OuterVision Power Supply Calculator (standalone version). It lets you factor in capacitor aging, overclocking, and how many USB devices you have plugged in. The DIY Method (Pen & Paper) If you want to understand the math, here is the average power draw for modern components:
The secret sauce is simple: