I've always been a little curious about this. My current situation is I have 512 of pc2700 and 2x256 pc2100. Would my system perform better with just the 2700 or with a full gig of the mixed? Would it be worthwhile for me to get another 512 stick of 2700? I have an A7N8X which is capable of a dual channel configuration. This question also goes for other situations as well. like pc 3500 with higher timings vs pc 3000 with lower timings/latencies.