There are 2 file types use the .OEM file extension:
1. OEM Setup File
Original Equipment Manufacturer (OEM) file used during the text-mode setup of Windows operating systems; contains a list of hardware components, files to copy for each hardware component, and a list of registry keys and values to create for each component.
OEM files are commonly used to bootstrap Windows operating systems load specific device drivers. A common OEM file that is used in Windows setup is called txtsetup.oem.
Updated: November 28, 2009
2. OEMEdit Save File
File created by OEMEdit, a program used for editing the OEM data on Windows Vista, Windows 7, and Windows 8 systems; saves manufacturer and system model information, a reference to a logo graphic, and optional support information (telephone number, etc.); can be used for applying the same system information across multiple computers.
You can apply an OEM edit by clicking thebutton on the OEMEdit interface. You can view the updated OEM information in the Windows Control Panel under System and Security → System.
NOTE: OEM files saved by OEMEdit do not use a filename prefix and are named .oem.
Updated: September 28, 2012