Windows 10: How to fix boot to disk in Windows 10 v1607 with legacy BIOS

Hello,

I have an Asus U46E laptop (circa 2011) originally purchased with Windows 7 Ultimate 64Bit and problem free. It's since been upgraded to Windows 10 Pro 64Bit v.1607 and in all respects but one seems to be working fine. It won't launch from a rescue boot disk in the D: disk drive.

I researched as much as I could about this issue and the PC's System Information shows the BIOS Mode is Legacy and Secure Boot is Unsupported. My boot-up order shows device before HDD and every reboot confirms the disk drive is being accessed and spins the disk before moving on to the HDD. This issue apparently has something to do with Windows 10 UEFI and its Secure Boot feature, which also speeds up boot-ups.

I've tried every combination of boot-up keys, F2, F8, F10, F12, with and without shift+ and also tapping the F key or holding it down. Shift+ Restart F2 gets me into the UEFI Settings>Troubleshooting>Advanced>Startup Options> Restart but it still won't boot to the rescue disk or into any BIOS-like menu. It just continue to boo up the the HDD with Windows.

The bootable rescue disk which was accessible before updating from v1511 to v1607 was by Acronis. Now I've switched to Macrium Reflect and have created bootable rescue disks with WinPE v.10, v.5 and v.4 to see if the lagacy detail would help. None work.

I think the solution is to get into the BIOS (not sure if UEFI is BIOS) or the UEFI and turn off Secure Boot or Fast Boot but I don't see how or at least it's not following the instructions I've read. Can it be done via CMD window or Safe Mode? The downside is I'd lose the security of Secure Boot for the insurance to be able to use a rescue disk if needed. Can Macrium Reflect do a system backup restore without the rescue disk (Acronis needs their rescue disk in their free version)?

Thank you.

:)

 

HOW TO ENABLE DUAL BOOT IN EFI MODE

I should add that if your BIOS is in UEFI mode, you have to enable CSM compatibility mode to boot to Windows 7. Also, the hard disk has to be GPT-initialized to boot in UEFI BIOS mode.

If your Windows 7 is on a separate disk that is MBR-initialized, you would have to toggle between UEFI and Legacy BIOS mode in BIOS setting to boot each OS. Windows 10 can be run in Legacy BIOS and Windows 7 can be run in UEFI mode.

Secure Boot is not compatible with Windows 7, so also has to be disabled to boot Windows 7.

 

Installing and booting windows 10 on a GPT partition

Do you have a UEFI BIOS? This is the only way you can install Windows to a GPT disk, otherwise it can only be used to intialize data disks, especially if you want them to be larger than the 2tb limit Windows has for MBR (Legacy BIOS) disks.

GPT vs MBR Disk Comparison

To find this out, type msinfo in Start Search, in System Information look at the BIOS type. If MBR you most likely have Legacy BIOS. But you can boot into BIOS setup to check for UEFI settings that may be disabled, or CSM/Legacy BIOS that may be disabled.
To install to UEFI one must also boot the installation media as a UEFI device.

More here:
Clean Install Windows 10

and here:
UEFI BIOS vs. Legacy BIOS - YouTube

 

From a Command Prompt (Admin) run:

shutdown /r /fw /t 00

(those are number 00 not letter O)
What happens?

 

Thanks NavyLCDR.

After entering the command in the CMD (Admin) window, I got two lists. The first "Usage: Shutdown" shows a list of commands and an explanation of what they do. The second one "Reasons on this computer:" shows a list of planned, unplanned, etc. The last thing on the list states: "P 7 0 Legacy API Shutdown". I don't know if the "legacy" has anything to do with my issue. After that it shows the normal prompt C:\windows\system32>

 

It sounds like your computer is set to boot in Legacy Bios mode, which will not have any option to enable secure boot. The manual for your computer states that to get into the device boot menu, press ESC when you power on the computer. Repeatedly tapping the key on most computers seems to be the most effective way to get into it.

 

I just tried Esc again, both tapping it and holding it down, after pressing the start up button and before I start up and continually until the login screen. In every case the result is the same where the empty D: drive is accessed first for a second then it moves right on to the C: HDD and the Windows login screen.

 

You could open it up and remove the hard drive and try to boot it from the DVD.

 

Are you suggesting that as a test or workaround solution? I don't think it would be a solution since purpose of the rescue disk is for in the event of local HHD or system failure, I would use it to access a system backup on and external drive and restore the local HDD. If there's no local HDD to restore, then ... ??? I might as well swap in another HDD with a clone on it then, right?

 

Just as a test. Also, have you tried booting from a USB flash drive instead of a DVD?

 

Ok. No, I've never tried with a usb thumbdrive. I'm not sure where that boot option is in the startup order and I can't check to see it. But I can try it. What do I do? I have the Macrium rescue Win PE versions downloaded. Which one should I try and how do I get it on the thunbdrive - just copy it over? Also, can any other files be in the thumbdrive or does it have to be dediicated just for rescue with Macrium?