i think for dual channel ya put the two identicle sticks in slots 1 and 3, then the other one where ever, thats all ya gotta do tho
If he puts in that third stick, say bye bye to dual channel.
There is nothing to set software wise dude, but you don't have dual channel with 3 sticks....listen to the name. "DUAL" channel, dual means 2 not 3.
If the third slot is further away from the other two then I believe you need to put it in slots 1 & 3 for you to obtain dual channel, but as I said you can only use 2 slots. If you want 1.5gb of RAM then youw ont have dual channel.
if all else fails, refer to the manual or ASUS website to find out which slots give dual channel.
Or you can open up CPU-Z and on the memory tab it'll say 'DUAL' if it's running in dual channel.