So each channel can run with a different amount of RAM in it? Wow... that's the first I've ever heard that. Can it also be different speeds then according to Abit?
I was under the impression that both channels needed to have same size and same speed, but not necessarily the same manufacturer. So if he's got 1x512MB stick of PC2700 and 2x256MB sticks of PC2700 he'd need to put the 512MB stick in the slot nearest the CPU and the 2x256MB sticks in the blue slots furthest away... That's how it works on my motherboard.
:edit: Hmm, just read the NF7-S manual and it doesn't seem to mantion anything about dual channel... perhaps it doesn't matter then?