I was wondering if these new 800Mhz PIV's will have support on 533MHz 850E Boards.
AFAIK they'll run but at a much slower speed unless you massively overclock the 850E motherboard. For example, a 2.4/800 CPU has a multiplier of 12. If you put it in an 850E running at 533 MHz FSB, the resulting CPU speed will only be 1.6 GHz!
Voltage shouldn't be a problem.