Originally Posted by Kage
I wouldn't think so no. That should be okay. I'd make sure that you grouped them still though, having the 512mb ones next to each other, and the 256mb ones next to each other.
You can't dual channel that way. If you want to get the most and dual-channel, install your memory sticks according to this diagram.
5 2 5 2
1 5 1 5
2 6 2 6
I know this is all going to mash together, but put your sticks in in that order, from left, to right.