Question: are ddr and ddr2 interchangeable?
Answer: Compatibility of DDR2 with DDR DDR2 DIMMs are not designed to be backwards compatible with DDR DIMMs. ... DDR2 is a 240-pin module, DDR is a 184-pin module. Faster DDR2 DIMMs though, are compatible with slower DDR2 DIMMs. The memory would just run at the slower speed.