[MetalMilitia]

Im really not sure I am understanding what you have done. Could you take a picture of it or something?

Basically your northbridge should have a HSF attached with annoying little springy screws - on the base of the heatsink should be nothing but a thin layer of thermal paste where the core of the northbridge is.

Chances are the HSF is currently not getting good enough contact with the northbridge chip for it to do its job properly.