Maybe this will be useless, but it does not hurt ... And i don't think it has been reported so far ( If so, forgive me please

)
I remember some with dual-core AMD having issue like yours, Stabiz. And it was the cool'quiet who was active on the system. ( stutters; slow-down; speed-up ..)
I think with Intel the thing is called EIST (Enhanced speed step thecnology) ( something like that ..). Checking this in the bios is the way to go.
I don't want to give false hope, but who knows ..