Broken Heatsink?

[imported_Dave_]

Well to start with, My computer Was bought from a police officer that is in the server industry. It is an IBM Intellistation Z pro. Its an older machine but he had rigged it to be faster than any computer in my house. The processors are a quad core Xeon Chips 3.6 Ghz and just recently put in an ASUS ENGT430 1gb graphics card. i dont remember much about the hardware inside at the moment. So onto the problem. After two days since i bought it, The computer would go into "Server Protection mode" (That what the cop said after i asked him about the problem) Usually dealing with keeping the CPU from frying. I know when the error occurs, when my monitor says "Going to Sleep" and my computers fans pick up and makes the computer useless for about 8 hours. I felt the inside and its not hot at all. in fact the fans are working quite nice. Now recently i was thinking it was a bug, Because it has been running so well for the past 12 hours. (Usually lasts 4 hours untill the error.) I left the computer alone for about 10 days and finally could muster up the guts to check the starting temp. When I looked i saw a rough 135C (275F). I thought there was no way in hell sitting in a 70F room for 10 days am i going to start up my comp at 275F. This morning it hasnt booted up yet. Happens quite often. Ive come up with two reasons of why this has been happening. #1 - Broken Heatsink. #2 - not enough Heat transfer jelly on the CPU.

Is there anyway i can fix this computer? I dont really fancy buying a new server tower.

(By the Way its for a gaming Server)