In the last few weeks my computer has started, well, pulsing. Its mostly constant, at a regular rate of about one pulse a second, and very low frequency, so the entire case resonantes. I've tried stopping each case fan individually to see if that stops it but no joy, so its no individual fan.
I can only think of two causes:
1) as all 3 fans (front, back, and CPU fan) are 3 pin fans plugged directly into the motherboard, its possibly something the motherboard is doing, or
2) Its the PSU (being the only fan I can't stop) that is pulsing, and the case is resonating to it.
Has anyone ever come across something like this before?