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DDR2 vs DDR Modules

DDR2 memory modules have the same physical dimensions as their equivalent DDR counterparts, but have different pin configurations.

The table below compares the different modules for DDR and DDR2:

  DDR2 DDR
Unbuffered DIMMs 240-pin 1.8V 184-pin 2.5V
Registered DIMMs 240-pin 1.8V 184-pin 2.5V
SO-DIMMs 200-pin 1.8V 200-pin 2.5V
Mini Registered DIMMs 244-pin 1.8V —
MicroDIMMS 214-pin 1.8V 172-pin 2.5V


Because of different voltages and pin configurations, DDR2 modules will have a different 'key' or notch in their connector to prevent them from being plugged into an incompatible socket. DDR2 memory modules will only fit in systems and motherboards designed to specifically support DDR2 memory.

DDR2 and DDR Module Key Locations


Side by side view of DDR2 and DDR modules

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