ADLINK IMB-M42H - Manual (Page 50)

40 UEFI Setup Utility
Enable to launch the Compatibility Support Module. Only disable
when running a WHCK test. If OS is Windows® 8 64-bit and all
devices support UEFI, CSM can be disabled for faster boot.
Launch PXE OpROM Policy
Enables UEFI to run those devices that support UEFI option ROM
only. Selecting Legacy enables only devices that support legacy
option ROM only.
Launch Storage OpROM Policy
Enables UEFI to run those devices that support UEFI option ROM
only. Selecting Legacy enables only devices that support legacy
option ROM only.
Launch Video OpROM Policy
Enables UEFI to run those devices that support UEFI option ROM
only. Selecting Legacy enables only devices that support legacy
option ROM only.