I had two ddr2 A-data Pc-6400, 2x 1 gig - Yesterday I bought two A-data ddr Pc-6400, 2x 2 gig so that's 6 gigabytes in total. At first I got a blue screen when booting up my computer ( got my bluescreen at the windows logo)
At first I thought that the problem was that I was using windows 7 32-bit so I installed the 64-bit version but I'm still getting bluescreen.
It's working with one 2gig and one 1gig but not with 2x 2 gig. And they are not working all 4 memories together.
Motherboard: Gigabyte GA-MA 78G-DS3H
the RAM must be the exact same model and specs in order to work. You have one set of DDR and the other is DDR 2 according to your post, not to mention they're different size and maybe different Mhz. Remove the 1gig RAM and use the 2Gb in their respective slots in order to use dual channel. Remember, they need to be the same spec and model, and installed in the right slots too. Consult your motherboard manual for details.