The power supply doesn't just run the power to the different parts of the CPU. It needs to run different voltages to different parts, and besides that, it has to deliver them within a very tight range set out in the ATX standard
Learning how to inspect your power supply and how to replace it when needed can be a life saver if you're a CPU buff or in Company with the trusted PC. Don't take for granted the simple pleasure of turning on your PC and everything works just fine.
