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