Abstract: A personal computer (PC) main board is used for mounting therein a memory module, and the memory module is capable of mounting therein one selected from a first type of Dynamic Random Access Memory (DRAM) and a second type of DRAM. The PC main board includes a memory module slot for replacably inserting therein the memory module and providing an operation voltage thereto, a switch device electrically connected to the memory module slot for changing a switching mode to adjust the operation voltage and an electric interface mode of the memory module in response to the type of the memory module, and a chipset electrically connected to the memory module slot and the switch device for switching operation modes between the first type of DRAM and the second type of DRAM in response to the switching mode of the switch device.