Calculate your PC's power consumption and find the perfectly sized Power Supply Unit.
Choosing the right Power Supply Unit (PSU) is the most critical safety decision when building a custom PC. If you buy a PSU that is too weak, your system will randomly crash, shut down under load, or potentially damage your expensive components.
Our PSU Wattage Calculator takes the heavy lifting out of the equation:
Power supplies operate most efficiently and quietly when they are at 50% to 70% load. Additionally, modern high-end GPUs experience "transient power spikes"—brief moments where they draw significantly more power than their official TDP. Adding 20% to 30% headroom ensures your PC remains stable, your PSU fan stays quiet, and leaves room for future USB devices or mild upgrades.
The 80 Plus rating (White, Bronze, Gold, Platinum, Titanium) measures energy efficiency from the wall outlet, not power capacity. A 750W Bronze PSU and a 750W Gold PSU will both safely deliver 750 watts to your PC components. However, the Gold unit will pull slightly less electricity from your wall outlet to do so, lowering your electricity bill and generating less heat.
No, having a PSU that is "too big" (like buying a 1000W PSU for a PC that only draws 400W) will not damage your computer. The PC only draws exactly what it needs. The only downside is that you are spending extra money upfront, and massive PSUs can be slightly less energy-efficient at extremely low idle loads.