from my own experiences...amd cpu has it's limitation regarding the max cpu speed you can get..and it's a lot more voltage sensitive than heat sensitive...
i had a duron 650 before, and no matter how hard i tried..the max i can get out of it is 950...and although it will boot at 1000, it will not load windows...and that's at max voltage of 1.85v...(switched from stock hsf to fop32-1 to fop3-1 ++, and finally alpha) although better cooling will give you better protection from cpu damage..it will not help you oc all that much..