Dual-channel requires the two memory modules. DDR2 doesn't require matching modules. DDR2 Wiki link explaining more.
Dual-channel Wiki link that may help. "How Much System Memory is Really Enough?" link that has an example of various configurations.
Hello to all!!! I have a question about how to best take advantage of DDR2. What (very) little I do know is that you need to use two memory modules (making sure they are in the right slots for DDR). My question though is this. Do the two modules need to be the same size or can they be different? I know the speeds should be the same, otherwise the default to the slower one. I wanted to upgrade the RAM on a friend of mine's desktop. He has one 256MB module (I know, I know). The system supports DDR2. Should I just get one 1GB RAM module for the other bank (his desktop has two RAM slots) or should I buy two 512 modules and replace the 256? Any help you can provide would be greatly appreciated. Thank you for your time.