My latest experience in overclocking AMD 9850BE inspired me to write some words for those who will go this way. This CPU, as you know, have unlocked multiplier so I start moving it higher - upto x14. Only this particular setting in BIOS - system works fine in Windows XP 32 bit = 2,8 Ghz work stable as with default value, but Vista 64 give BSOD. Playing with different CPU voltage settings I make it work - but feeling of stability gone. I try to find out whats the reason of such different results - working well in XP and crashing in Vista 64. Was found that overclocking in 64 environment- both XP and Vista make system less stable , perhaps of tighter timings. Another part of the problem - chipset - people got better results with 64 bit vista overclocking on AMD chipsets (790fx e.g) rather then on nVidia 780a chipsets. Maybe some BIOS bugs take place, maybe different motherboard have difference in voltage stability - nobody knows it for sure.
So, if you plan to overclock your AMD system and you using 64 bit OS - best choice is DFI motherboards with 790fx chipset.