According to the problem you have just described, probably you are having problems with your fan(s) in the CPU or hard-disk
There are 2 fans in ur CPU which is power supply fan and CPU fan. You might want to check them! But be careful..If you want to check CPU fan, turn off ur PC and wait for it to cool off. Then open the case and see. If its CPU fan's problem, u ll need to replace it since if u dont, ur CPU is at risk of burning.
If its power fan, dont ever attempt to fix it by urself. Just go and replace with a new one.
You might want to check the hard disk too. Since strange noise from hard-disk could be a signal that ur hard-disk might crash:( You can refer to this website for more clarification
Hope this helps:)