Well 850e does not offically support PC1066, but Intel is not going to prevent people from running their RAM at PC1066. Even their own D850EMV2 can run at PC1066, because Anand did. I just thought I'd add Fkloster, even at PC1066+533fsb, they are not in sync. PC1066 runs at 533Mhz DDR, meanwhile the front side bus runs at 133MHz QDR, the system isn't going to care that the "effective" speed of the fsb is 533MHz. This is why you still have to use 4x RDRAM-fsb multiplier.