Me thinks everybody is missing the point with this thread, Chandler 44 is talking about adhesive thermal pads, like double sided tape that holds the heatsink in place.
Normal Artic Silver won't hold the heatsink on!
I have heard of a thermal compound adhesive (epoxy thermal resin) that literally glues your heatsink in place. Kind of think Artic Silver make it?? not sure, one thing is though I remember it being expensive!!!
And No!! applying AS to the exsisting thermal adhesive pad will render it non adhesive, back to square one again!!
only other thing would be to fit the plastic retaining clips like the kind some chipset heatsinks use, but this may involve drilling holes in the PSB, rather U than ME!
Martin