09-19-2017 02:46 PM - last edited 3 weeks ago by ROGBot
09-19-2017 03:22 PM
09-19-2017 03:42 PM
Nate152 wrote:
Hi R5EandMe
I'm pretty sure windows 10 comes only comes on a usb drive.
You'll want to make sure the M.2 slot is set to PCIe x4.
I don't have an M.2 drive but installing windows 10 should be basically the same. I disable CSM and set Secure Boot to Other OS then set Boot Option 1 to the windows installation usb drive.
F10 and Enter to save and exit, upon rebooting you'll get an option screen, select windows 10 64-bit. Then I select custom (advanced) install, delete all the partitions and let windows create the partitions.
Be sure to disconnect any other drives before installing windows.
How does this work for you ?
09-19-2017 05:07 PM
09-19-2017 06:21 PM
Nate152 wrote:
I'm pretty sure with CSM disabled the other drives don't show but they still work.
You can let CSM enabled, it will just add a few seconds to the boot time.
09-19-2017 06:29 PM
09-19-2017 07:08 PM
Nate152 wrote:
Well I only have two options for Secure Boot and they are Windows UEFI and Other OS. I have to have Secure Boot set to Other Os or I get a message saying unauthorized changes have been made to the OS.
09-19-2017 07:21 PM
09-20-2017 02:42 PM
05-09-2018 12:53 PM
R5Eandme wrote:
I figured out why in the pre-Windows installation environment and with CSM disabled that I could not see any of my storage devices in the “Boot Option Priorities” or “Boot Override” lists.
Back in the old days of Legacy BIOS booting, all storage devices showed up in boot lists where you could arrange their priorities and select one to boot from. Now with UEFI BIOS, only UEFI-bootable devices show up in those lists, unless you have enabled CSM. Disabling CSM is for UEFI-only booting, and the only devices that show up in boot lists are devices that contain \EFI\Boot\bootx64.efi in the root directory. That is the UEFI "boot loader". If I had installed Windows on the Samsung 960 Pro then \EFI\Boot\bootx64.efi would appear in the EFI (“System”) partition of the drive, and the boot list would show "windows Boot Manager" or “UEFI: Samsung 960 Pro” or something like that.
The DVD drives did not show up in the boot lists with CSM disabled because they did not contain any disks. If I insert the Acronis/WinPE rescue disk before booting into BIOS, then the DVD drive shows up as “UEFI: Pioneer BD-RW BDR-209M” because that disk contains the directory \EFI\Boot\bootx64.efi. Same for a Windows 10 Recovery thumb drive I made for a different computer, for booting into the WinRE environment. It shows up in the boot device list as “UEFI: SanDisk Ultra USB 3.0 Flash Drive” because it too contains \EFI\Boot\bootx64.efi as I’ve verified.
So with CSM disabled, the ASUS UEFI Bios will examine all HD, SSD, USB ports, and DVD drives, looking for UEFI bootable devices that contain \EFI\Boot\bootx64.efi. In contrast, if CSM is enabled then all devices show up whether or not they contain \EFI\Boot\bootx64.efi. With CSM enabled you will then see two versions for example “P3: Pioneer BD-RW BDR-209M” and “UEFI: Pioneer BD-RW BDR-209M”, giving you a choice of booting to the device with a Legacy BIOS boot or a UEFI boot. The Legacy boot will not use the \EFI\Boot\bootx64.efi boot application, but will instead use the application named bootmgr.
So I can in fact leave CSM disabled and install Windows, and if I ever need to boot from an Acronis rescue disk or a Windows Recovery thumb drive, I can either press "F2" or “DEL” and boot into bios and select the device from the “Boot Override” list, or spam the “F8” key during boot after the ROG logo appears, to bring up the “Please Select Boot Device” menu which will list all devices containing \EFI\Boot\bootx64.efi. If I ever need to boot from a non-UEFI compliant device that does not contain \EFI\Boot\bootx64.efi then I'd have to enable CSM first if possible (and probably have to disable Secure Boot). That is my understanding.
CSM IS ENABLED BY DEFAULT, so people who want a pure UEFI boot system will want to disable CSM before installing the OS.
Here are some good resources I found:
A Youtube video: “How to Fix Issue Booting to DVD/CD with New UEFI BIOS Boot Order” https://www.youtube.com/watch?v=y8Ml1IbVp-8 where he had an Acronis rescue disk that did not contain \EFI\Boot\bootx64.efi, and so he had to go into BIOS and enable CSM & disable Secure Boot in order to boot from it.
Also an old but excellent and still relevant discussion by Sushovon Sinha “UEFI Secure Boot in Windows 8.1” https://answers.microsoft.com/en-us/windows/forum/windows8_1-security/uefi-secure-boot-in-windows-81... which is full of good technical information.