Many things can go wrong during a PC build. One of the most popular mistakes is buying incompatible components. This is why I suggest using PC Part Picker to make sure all of your components are compatible. Cheap PSUs can be a real problem. A very generic PSU could result in a house fire, so always buy a high-quality PSU from a trusted brand. Last but not least, READ THE MANUALS. If you don’t install the components according to your manual’s instructions, you might have to restart the build process or even risk damaging a component.