User Manual
Page 69
Please do not disable unless you may also disable CSM for faster boot speed. If you are using Windows 8.1 64-bit and all of your devices support UEFI, you 're running a WHCK test. Select Legacy ... Policy Select UEFI only to run those that support UEFI option ROM only. Select Do not launch to launch the Compatibility Support Module. CSM (Compatibility Support Module) CSM Enable to not execute both legacy and UEFI option ROM. 64 English Select Legacy only to run those that support legacy option ROM only...
Please do not disable unless you may also disable CSM for faster boot speed. If you are using Windows 8.1 64-bit and all of your devices support UEFI, you 're running a WHCK test. Select Legacy ... Policy Select UEFI only to run those that support UEFI option ROM only. Select Do not launch to launch the Compatibility Support Module. CSM (Compatibility Support Module) CSM Enable to not execute both legacy and UEFI option ROM. 64 English Select Legacy only to run those that support legacy option ROM only...