dual channel woes

[borat]

got a new DFI nf2 infinity ultra and 2x521Meg muskin pc3500 level 2.

i can run stable with a single 512 dimm in at 210Mhz 2-2-2-6 on both sticks of memory, but when i run dual channle it wont even run stable at 200Mhz, anybody got any ideas as to why this could be?
cheers
will

[ayoub_ibrahim]

what vdimm are you using?

[borat]

using 2.7, 2.9 and 3.1, none of them seem to want to work. I used an unsupported tictac bios, and it booted striaght off and worked fine at 210 dual channel, but all is not well as my mates exact same motherboard with my memory boots up dual channel at 210Mhz without problem using the stock bios. Think i may have a dodgy motherboard. Am a little dissapointed i cannot push the BH5 any further than 210 too considering its PC3500, once again though i think that this is more to do with the mobo as it doesnt make a difference even if i relax the timings to 4 4 4 7 with 3.1V. Looks like an RMA job, @sigh@