I tried the RAM out of the good PC, but I didn't reinstall windows. It already installed from the other pc. It loads the windows startup menu now but it wont go into safe mode or load windows normally. It just hangs or freezes again,, even in the middle of the countdown to start windows normally on the startup menu.
so was it a faulty RAM stick?
I installed the heat sink and fan the only way I knew how. I watched vids and everything to make sure I was doing it the right way. Maybe it was the thermal grease I used, cos it was awful thin. I dont know. I'm just guessing

if i were to get a new heat sink and fan what would i buy like the size, speed or whatever else i need to know?

You really need to try the install with the ram from the other computer. If it installs fine then that is the problem. If your computer was overheating in would generally shutdown not freeze.

You can try doing just a repair install with the ram from other pc. Also try using just one stick of ram when you re-install windows.

i tried the install with good ram, but the same thing occurred. I did, however use another heat sink and fan from another computer (a) and another hard drive from an additional computer (b). But when I hooked up the hard drive to my mobo, it asked me to activate windows. I also had to install drivers from the motherboard disk that was supplied with my computer. So does that mean my hard drive failed? I am also using my RAM, not the one from computer (a) but from my computer. What is the best way to tell if the hard drive is bad or gonna fail?

Fay hello.no HDD has not failed (I hope)some times when adding new hardware to a computer you do have to activate it again.
I have added RAM to a computer and rebooted and had to reactivate.

Have you also tried a reinstall of the operating sytem?Using the old hard drive?