Yes, the cards have the stock fans and heat sink.  I'd be very suprised if this issue was caused by the heatsink.  My thinking is either the bios or hardware is fried....?

the silver shim around the GPU is there... slightly scratched, but its there.

UPDATE:  ok I stand corrected.... I took the heatsink off and I clearly didn't put enough thermal compound on.  Actually I think it was enough... but that shim does create a slight gap, so more compound is needed.  I put the card back into the PC.. started it up and yes.. it improved.  Temporarily :p the temp started at 60 and gradually got to 98, where the core clock started to throttle again.  So the probablem still persists of it getting too hot and throttling.  Whats next.....:s