Rules to Enable Dual Channel Mode
To achieve Dual Channel mode, the following conditions must be met:
Matched DIMM configuration in each channel
Same Density (128MB, 256MB, 512MB, etc.)
Matched in both Channel A and Channel B memory channels
Populate symmetrical memory slots (Slot 0 or Slot 1)
Configurations that do not match the above conditions will revert to Single Channel mode.
The following conditions do not need to be met:
Same timing specifications
Same DDR speed
Memory channel speed is determined by the slowest DIMM module populated in the system.
*This really depends on your motherboard. Some manufacturers use a color
-coded system (meaning use the same colors) and some require that you use the symmetrical approach (meaning same slot on both channels).
ok, that pretty much answers my question. I bought a new board and gave him my Asus M4A77TD board that has 2 blue and 2 black slots. So if down the road I buy another of the same stick and say for instance place them in A1 and A2 it should work as dual channel right.
Keep in mind that mixing RAM often leads to boot or performance problems. By mixing RAM, I mean if you have specs that differ from each other. I would recommend you get an identical stick of what you just purchased now, if you are seriously thinking about adding another 2GB later.