PRIME X470-Pro can't boot from USB in UEFI mode, preventing Windows 11 installation

[leocomerford]

Hello all,

A family member has a PC with an ASUS PRIME X470-Pro motherboard, a Ryzen 5 2600X processor and 16 GiB of RAM. The PRIME X470-Pro is one of the motherboards featured on ASUS' "ASUS Motherboards Ready for Windows 11" microsite https://www.asus.com/microsite/motherboard/asus-motherboards-win11-ready/ . In fact this PC used to run Windows 11, until Microsoft tightened the requirements and it started to fail to boot without any warning. It has been back to running Windows 10 since then, but with the end-of-support deadline approaching it is necessary to try to upgrade again. The BIOS has been updated to the latest version, 6232.

Trying to upgrade to Windows 11 from inside Windows will not work, as PC Health Check complains that Secure Boot is not enabled. Indeed it seems that the current Windows 10 installation on this PC has MBR partitions on disk, so that's not surprising. The obvious solution would be to make a fresh installation of Windows 11 using a USB stick with the Windows 11 installer. Unfortunately, even with the BIOS up to date, with the motherboard CMOS freshly cleared, and with a Kingston DataTraveler USB drive, freshly configured as Windows 11 install media using the official Microsoft tool, inserted straight into one of the motherboard's USB slots, it is not possible to install Windows 11; because the motherboard simply will not boot a Windows installer from the USB drive in UEFI mode.

The problem is not that USB UEFI boot options fail to show up in the BIOS. The USB drive shows up twice, once as "UEFI OS (KingstonDataTraveler Max1000)" and once as "KingstonDataTraveler Max1000". But when that "UEFI OS" option is selected, the computer simply spends a long time displaying an ASUS splash screen, then bluescreens with Windows error 0xc00000e9, "An unexpected I/O error has occurred", file \windows\system32\boot\winload.efi . If the legacy-boot option is selected instead, the Windows 11 installer starts and runs normally until the actual install setup begins, when the "This PC doesn't currently meet Windows 11 system requirements" dialog appears. Presumably this is the installer finally noticing that it was started using legacy mode.

If it were possible to reinstall Windows 10 from USB in a Secure-Boot-compatible configuration, using GPT partitions on the M2 drive and so on, then presumably it would be possible to upgrade to Windows 11 from within Windows 10. Unfortunately a failure to successfully boot from USB in UEFI mode makes that impossible too. I used a freshly-generated official Windows 10 installer on another DataTraveler USB drive inserted directly into a motherboard configured with the current BIOS version and with a freshly-cleared CMOS. Again both a "UEFI OS" and a non-UEFI option to boot the USB drive appear in the BIOS. Again the "UEFI OS" option spends a long time on the ASUS splash screen, about 10 minutes: then the computer shows a blank blue screen for a few seconds, then finally shuts down. Selecting the non-UEFI option allows the Windows 10 installer to boot as normal. Unfortunately, because the W10 installer was started in legacy mode it will refuse to make or use any GPT partitions on the computer's M2 drive, and it will only make a legacy-boot installation of Windows 10 using MBR partitions.

To try to confirm that there's nothing wrong with the Kensington DataTraveler USB drives or the Windows installers saved to them, I used the DataTraveler drive with the Windows 10 installer to boot another Windows PC, using UEFI mode. Everything seemed to run successfully: in particular, this time the disk manager would only attempt to install Windows on GPT partitions and refused to use MBR partitions.

I also installed the Windows 11 installer on a different manufacturer's USB drive ("Intenso Business Line 8.07") and tried using that to boot my family member's PC. The results were the same as when I used the DataTraveler drive (except that it booted, or failed to boot, more quickly, for some reason).

I also created Windows 11 installers (not Windows to Go drives) using a Windows 11 ISO and the Rufus bootable drive generator (with a GPT partition and a UEFI bootloader, naturally). I installed one on one of the DataTraveler drives, and one on the Intenso drive. When I attempted to boot in UEFI mode on my relative's computer using these drives, the computer went from showing the ASUS splash screen, to showing a blue screen, to shutting down (as before, more quickly with the Intenso).

I also tried using a different (TDK-branded) USB drive installed with MemTest86 (an old version from 2021, 9.2 ). Strangely, this booted and ran successfully in UEFI mode.

I reflashed the v. 6232 BIOS using the in-BIOS EzFlash utility. It didn't seem to change anything, but since this problem has persisted over a number of years and BIOS updates that wasn't surprising. I'm not sure if I've ever seen UEFI boot from USB work consistently on this motherboard.

What should I do? Ideally I would be able to find some way to fix or work around the apparently broken motherboard to make the motherboard consistently boot from UEFI USB drives. I suppose I could also look into doing a UEFI network boot, or getting a Windows installer on a SATA device, though I have no idea if that would work any more reliably than UEFI USB booting. Alternatively, if I could somehow turn the MBR-and-legacy-boot Windows 10 installation into a GPT-and-UEFI Windows 10 installation in place, without reinstalling, that might work ... or it might not. It would also leave us in an awkward position if we ever need to reinstall Windows on this machine.

[leocomerford]

Thank you for your reply! Unfortunately, the issue with Windows installers (the W10 installer won't create or use GPT partitions if it's booted in legacy mode, while the W11 won't install anything at all if it's booted in legacy mode) means that Windows can't be installed to GPT partitions in that that way. In any case, I think it's likely that UEFI boot largely doesn't work on this motherboard at all, no matter what type of boot device is selected. In particular, using MBR2GPT to convert an existing MBR Windows 10 installation on the M.2 drive to GPT fails, with the same error that we get when attempting to boot the W11 installer in UEFI from a USB drive.