Right now I'm running an i7 950 and 5970 with 6gigs of 1600mhz 6cas Triple Channel Ram. I was using dual channel at first (8gigs) even though my board is specced for Triple. It worked fine. Both sets are 1600mhz and 6cas latency. If I put in the dual channel with the triple will it drop preformance? I will be adding 6gigs, so I wasn't sure if its worth keeping my 6gigs triple or adding some dual channel.
Not much difference with 6 or 8 gb of ram in performance. I would use the same brand of ram and not mix them. If you must mix them, try all 6 ram slots filled of the same size and speed. Dual or tripple is moot.