Open a command prompt (elevated, preferably), and...
for /l %X in (1,1,100) do winsat formal
Windows Vista and 7 only, though (only they have WinSAT).
(edit: Oh, and Ctrl+C to stop/cancel it)
Bam, WinSAT burn-in testing. Tests GPU, CPU, RAM, and HDD. Ultimate stress testing. No download required.
Edited by FalconFour, 24 December 2010 - 08:12 PM.