A common problem when building a computer is: How big of a power supply do I need to be able to push the computer? If I buy one that is too big, I think it will be a waste because it does not use so much wattage. If I buy one that is too small, I am afraid that it cannot push the computer. Moreover, I have to consider whether new computer parts can be used when I get sick in the future. It is better to buy now. Most of the power supplies have a 5-10 year warranty, and the most common ones also have a 3-year warranty. This means that after you buy a better power supply, it should not be a problem to use it with two computers (replace it every five years). So how many watts should you choose for the power supply? MSI here provides a very useful gadget :

(MSI power computing website)
The method of use is also very simple, based on the computer I will build next month. After filling in the configuration information truthfully, the system will give wattage recommendations based on the configuration. It will also recommend a power supply that is slightly higher than the recommended wattage. For a system like mine, it is recommended that 393 watts be needed. In terms of my habits , at least I will get a gold medal power supply of 650W or above to ensure the safety of the power supply, and when setting up a computer, be careful not to save money on the power supply. A good power supply can really make your computer work safely, and now the warranty is so long-lasting. After careful calculation, this investment is very cost-effective!

(MSI power computing website)
Source: KOCPC Chinese