I just put in a new Zalman Heatsink for my CPU. When the computer is idle my Nvidia system monitor shows 50 degrees. But when I play any game the computer freezes and crashes. I think it's the CpU because it has overheated a couple times before that. I want to know if the CPU is done and I need a new one or is it something else? Thanks
Sounds to me like you didn't get the heat sink mounted correctly.
Did you clean all the old thermal paste off completely?
Did you use the proper amount of new thermal paste?
Did you get the heatsink mounted perfectly flat and tight?