T5600 not built to sustain high cpu load?

Hello all, 

A second hand equipment vendor is claiming a fried cpu was my own fault, as the "little fan" in a T5600 can not support 75% cpu load over time. As such, they will not cover the defect under warranty. 

Sounds like utter nonsense, any workstation should have sufficient cooling to handle even 100% cpu load for any length of time. 

Might there be some way to prove to said vendor that Precision workstations are indeed designed to run such workloads?

Best,
Roy