GfK,
I had a similar problem before.
I changed *everything*. CPU, Memory, Hard Drive, PSU,GFX card, all add-ons etc...
Turns out that somehow the case was causing it- running the system outside of the case worked- so I got it a new case and all was gone.
I really don't know what actually *caused* the problem though... I even changed the motherboard and was absolutely gobsmacked when the problem was still there!
I had a similar problem before.
I changed *everything*. CPU, Memory, Hard Drive, PSU,GFX card, all add-ons etc...
Turns out that somehow the case was causing it- running the system outside of the case worked- so I got it a new case and all was gone.
I really don't know what actually *caused* the problem though... I even changed the motherboard and was absolutely gobsmacked when the problem was still there!