Stress testing - buzzing noise.

[Inazuma]

Hi
At some points during stress testing my Q6600 3.4ghz (+4GB Geil ULL), I hear quite an audible high pitched buzzing noise. Does anyone else get this? Does anyone know the cause?

 

[Inazuma]

Ok cool. It isn't loud, but I can hear it faintly from 3 feet away.