HI, I have gigabyte motherboard model no GA-8I865GME-775-RH . I checked on the website it says that it supports Dual Channel DDR400 memory architecture. what is ddr400 memory and can install a ddr2 1 gb ram in the same motherboard.
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No, DDR2 won't physically fit in the slots.
You need to search for DDR-400 when purchasing memory for that board. That will get you the right speed and type of memory so it will work for you.