Windows X64 Lowers Overclock?

I had Win XP Pro 32 and could get into windows stable at 2700mhz with 1.58-1.6 volts, now i cant get past 2650 on X64.

Do you think the OS puts more strain on the processer since it is using 64 bits?

Thanks for the replies.

I had a similar problem.. I could clockgen my opterons to 2.15 stable, and 2.4 on a suicide run.

XP64 Stops me right around 2ghz. I don't know what I'm gonna do.. It seems XP64 is performing worse in most cases.. Sucks to waste those bits tho ;- ]

That's quite true... On many suicide runs on this CPU @ 2.70 ghz, it would run SPi with no problems..

After some benching, I gave HL2 a go (64bit engine now), and I got a blue screen just as it started to load.

I guess I could probably run 2.7 stable on a 32bit environment, but I'm happy with 2.65 and 64bit environment

dan