I have a Gigabyte GA-965P-DS3 motherboard. I have (2x1GB) CorsairTwinX XMS2, DDR2 PC2-6400. I want to install another (2x1GB) CorsairTwinX XMS2, DDR2 PC2-6400. When I install all 4 modules the computer wont boot to windows. If I remove one module it boots fine. I have tried all combinations of modules and slots. All the modules work OK when on their own, in pairs or 3 modules together but not when all 4 are fitted. So from my conclusions the modules are fine and the slots are OK. Any ideas on what might be causing this to happen?