This is how i understand it. To get dual channel DDR to work you need a motherboard with a chipset like nforce 2 that supports it. Then you need 2 standard DDR memory modules of the same type and size. Put those in and you get extra bandwith. If you installed 2 512mb ddr in Dual mode you should get 1024mb. I may be wrong though?
The simple way of explaining Dual DDR is just how the memory is accessed, instead of all the Ram being in One channel with like 3 or 4 slots (or memory banks) what they have done is basically split it in 2's (channels) of 2 slot or banks each. Now the way information is transfered and accessed is a bit differnt and faster. That is a very butchered and basic way of looking at it
So if I install 3x256 DDR333, then will two work wih dual channels and one work with single, or are all three are working as single rams? Installing 3 Dimm's will not make the dual channel work?? Thanks