All your PSU does is provide power.
If all those other things are happening, you have some other problem.
A hard drive being at 100% constantly is normally a sign that the hard drive is failing and is taking way too long to read or write something.
The first thing you should do is to backup anything you want to keep that is on that drive. The sooner you get a backup made, the better off you will be.
Once that is done, I would open My Computer or This PC, right click on that drive (probably C

, select Properties, and then the Tools tab, and then Check Disk.
See if any errors are found. Sometimes, Windows can replace bad sectors. But if there are a lot of them, it is best to replace the drive before it fails.
If no errors are found, then something else is causing the drive to constantly be busy, and you need to find out what it is.