H81M-C User's Manual
Page 64
... this item is set to [Enabled], the system waits for the F1 key to be displayed only if the third-party manufacturer had set Launch CSM to launch. Boot Device Control [UEFI and L...] Allows you want to [Enabled]. Configuration options: [Legacy OPROM first] [UEFI driver first] [Ignore] 2-... will be forced to fully support the Windows® Security Update and Security Boot. The following four items appear when you to configure the CSM (Compatibility Support Module) items to fully support the various VGA, bootable devices and add-on devices or the Windows® UEFI mode. [...
... this item is set to [Enabled], the system waits for the F1 key to be displayed only if the third-party manufacturer had set Launch CSM to launch. Boot Device Control [UEFI and L...] Allows you want to [Enabled]. Configuration options: [Legacy OPROM first] [UEFI driver first] [Ignore] 2-... will be forced to fully support the Windows® Security Update and Security Boot. The following four items appear when you to configure the CSM (Compatibility Support Module) items to fully support the various VGA, bootable devices and add-on devices or the Windows® UEFI mode. [...