A common module for a double data rate-synchronous II synchronous dynamic random access memory (DDRII SDRAM) and a DDRIII SDRAM applied in a computer is provided. The common module includes a first bus, a termination circuit card, a first slot, and a second slot. The first bus transmits a plurality of signals. The termination circuit card comprises a plurality of termination resistors. The first slot is disposed on the common module and coupled to the first bus. The DDRII SDRAM is installed in the first slot. The second slot is disposed on the common module and coupled to the first bus. The DDRIII SDRAM or the termination circuit card is installed in the second slot. When the DDRII SDRAM is installed in the first slot, the termination circuit card is installed in the second slot.