Sounds like a case problem.
Anyways there is nothing wrong with a cpu hitting 80, only if that 80 is prolonged for like 8 hours. Hell the i7 doesn't crap out untill 110-120 or so (but intell wont let you pull that stunt, down clocks when hitting 100). I pushed the i7 here to 98 before, but that was at 3.2ghz running prime95 with the default fan w/ no thermal paste. I lowered it down to 3ghz.