In an video created by JayzTwoCents he went into depth on his particular build by stress testing it with a Watt meter attached showing what the actual requirements of his build was.
He went on to actually stress testing his CPU and GPU and showing the wattage as it moved up and down. Now most people aren’t going to go this in-depth with figuring this out as they are looking to build it not stress test it. Some things to really look out for when your trying to pick your PSU would be some of the following.
1. How much power is required from my processor?
*For Example* on a Intel® Core™ i9-9900T Processor (16M Cache, Up to 4.40 GHz) the average TDP (Thermal Design Power) is around 35W at base operations.
2. How much power is required from my graphics card?
*For Example* on a NVIDIA RTX 2060 SUPER the card power requirements are 175W. NVIDIA calls for a recommended 550W PSU.
3. Some other things that your going to want to take into consideration would be what types of accessories are you trying to add to your computer i.e. extra fans, RGB’s, Radiator, sound card, RAM, etc..
4. Overall make sure you do your research on what the requirements are of your computer build so that you can get the most bang for your buck.