Having a quality power supply is essential to any computer. It takes in power, filters it and converts it into clean power for your components.

It's best to stick to well known brands of PSUs as there are many poor quality PSUs for sale on the internet. Your system will run hot and may be unstable under load. Eventually other components will fail.

If you have a basic computer a 450W Bronze PSU will serve you well. Larger 550W models will give you room to fit a passive Graphics card or more storage drives.

Bronze PSUs are 80 percent efficient at 20% load, but only 50% effficient at higher loads. A 650W Bronze PSU is cheap to buy and would be good for an i3 or low end i5 with integrated graphics. You could also run the same system with a GeForce 3060 for example.

Gold and Platinum PSUs are recommended for gaming and workstation use. As they will be pulling more power and will save you money in the long term. A 750W PSU can be used with a GeForce 4070 but an 850W PSU will give you more headroom.

High end i7 computers and above would benefit from a 1000W or higher PSU. If you are lucky to have a Threadripper or high end GPU consider nothing less than a 1300W PSU.

Look for a case that has a separate chamber for the PSU. It should have it's own intake and exhaust separate from the motherboard and other components.