Is Fast Boot disabled? Have you tried changing the settings of CSM (Compatibility Support Module)?
* CSM (Compatibility Support Module)
This item allows you to configure the CSM (Compatibility Support Module) items to fully support the various VGA, bootable devices and add-on devices for better compatibility.
* Launch CSM
[Auto] The system automatically detects the bootable devices and the add-on devices.
[Enabled] For better compatibility, enable the CSM to fully support the non-UEFI driver add-on devices or the Windows UEFI mode.
[Disabled] Disable the CSM to fully support the non-UEFI driver add-on devices or the Windows UEFI mode.
The following items appear only when you set the Launch CSM to [Enabled]:
* Boot Devices Control
This item allows you to select the type of devices that you want to boot.
Configuration options: [UEFI and Legacy OPROM] [Legacy OPROM only] [UEFI only]
* Boot from Network Devices
This item allows you to select the type of network devices that you want to launch.
Configuration options: [Ignore] [Legacy only] [UEFI driver first]
* Boot from Storage Devices
This item allows you to select the type of storage devices that you want to launch.
Configuration options: [Ignore] [Legacy only] [UEFI driver first]
* Boot from PCI-E/PCI Expansion Devices
This item allows you to select the type of PCI-E/PCI expansion devices that you want to launch.
Configuration options: [Legacy only] [UEFI driver first]