My gigabyte P35 DS3R does 500FSB comfortably with both an E6600 and Q6600...
I get bad vdroop on my gigabyte board - the top (senesible) option 1.6v (then jumps to 1.8 with current BIOS
) only gives 1.55volts at full load on the CPU which isn't enough to get much beyond 3.7gig stable with the E6600 and 3.5gig with the Q6600.
EDIT: I say comfortably... I only ran orthos on 2 cores for about an hour with the Q6600 in - whether or not it would run through a full 24 hour priming on all 4 cores or not is another matter.
I get bad vdroop on my gigabyte board - the top (senesible) option 1.6v (then jumps to 1.8 with current BIOS

EDIT: I say comfortably... I only ran orthos on 2 cores for about an hour with the Q6600 in - whether or not it would run through a full 24 hour priming on all 4 cores or not is another matter.