A computer device, a setting method for a memory module, and a mainboard are provided. The computer device includes a memory module, a processor, and the mainboard. A basic input output system (BIOS) of the mainboard stores a custom extreme memory profile (XMP). When the processor executes the BIOS, so that the computer device displays a user interface (UI), the BIOS displays multiple default XMPs stored in the memory module and the custom XMP through the UI. The BIOS stores one of the default XMPs and the custom XMP to the memory module according to a selecting result of the one of the default XMPs and the custom XMP displayed on the UI.