BSOD after enabling multi-GPU in BIOS

My Dad runs a dual-boot Win 8 / Win 10 system. He uses Win 8 most of the time and Win10 is just for his flight sim, which he doesn't have a lot of time for so he doesn't boot into that very often.

Anyway, he asked me about using Zoom virtual background without a physical green screen and the criteria on Zoom's website indicated that it might work with his system with Win 10 with the Intel IGP enabled. He has an AMD RX 570 GPU which he uses normally. So, following my instructions, he enabled the Multi-GPU option in his Z97-A BIOS (with that disabled the IGP is disabled and doesn't show up in Device Manager if there's a discrete card plugged in) and now Win 8 Device Manager shows both the Intel 4600 IGP and the AMD RX 570 GPU but when he tries to boot into Win 10 he just gets a BSOD which he says refers to winload.exe.

I wouldn't have thought enabling the IGP could trigger a winload.exe BSOD but as I say, he doesn't boot into Win 10 very often so he probably hasn't touched it since I was last at his house and booted it fine and he won't have installed any strange software into it.

The dual-boot is using grub4dos, so I'm wary about running any automatic startup repair (although he says he tried this before phoning me) or manually doing fixmbr as that will probably wipe the grub4dos MBR and then he won't even be able to boot into Win8!

Is it likely that the Win10 BCD has somehow got corrupted? If so, I could try using BootICE or EasyBCD from Win8 to try and repair the Win10 BCD.

GRUB is very simple - you may be able to study up on it quickly (and then not worry about hosing it).

Let's have a look at the reports that are asked for in the Posting Instructions pinned topic:
BSOD - Posting Instructions
May be able to fix this without resorting to any exotic attempts at repairs.
If unable to get into W10, copy the minidumps from the Windows 10 Windows/Minidump directory, then zip them up and upload them with your next post (you should be able to do this from within W8).

If he's able to disable the Intel graphics and get into Windows 10 - the first thing to do is to update Windows 10 through Windows Update (to include any hardware updates that are available).

Finally, what sort of access do you have to his system?
- Physical
- Remote
- instructions that you pass to him

Thanks jdc1, I've got TeamViewer access to his PC. Normally I'd be able to go over there to fix stuff as he lives nearby but obviously I can't do that at the moment.

I use grub4dos myself and installed it for my Dad, so I'm fairly familiar with it, which is why I was worried my Dad might wipe it from the MBR and leave himself unable to even boot into Windows 8 if he tried doing the Windows 10 Startup Repair.

Luckily that didn't happen even though my Dad tried the Startup Repair before he called me. I managed to fix the Windows 10 problem over TeamViewer by running BootICE from Windows 8 and fixing the BCD. It had no partition set at all for the Windows 10 boot entry (which is the only entry in the Windows 10 BCD). My Dad did say he tried running some bootpart commands after Googling it, so it may be that what he did caused this but setting the partition has got Windows 10 booting normally, so it was probably messed up before he tried anything.

Strangely when I was in Windows 8 I couldn't find any minidump folder on the Windows 10 partition under the Windows directory and even searching the partition for minidump didn't find anything. I had "Hide protected operating system files" disabled in Windows Explorer.

WIndows 10 is updating with 1909 and a few other updates now, after which he's going to try enabling the multimonitor BIOS option again and rebooting back into Windows 10. I was able to check the driver version for the Intel 4600 by showing hidden devices in Device Manager and it was quite old, v19.xx I think from 2017 and Zoom's website says it needs to be v23.20.xx.xxxx or higher. Windows said the latest version was already installed, so I downloaded the latest version from Intel Download Intel(R) Graphics Driver for Windows* [15.40] but I couldn't install it as the IGP was disabled, so I told him to do that after rebooting with it enabled and hopefully that will do the trick.

Sounds like you've got a good handle on this.
Thanks for letting us know!
Good luck!

PS - backup the BCD and set a System Restore point. A data backup/disk image wouldn't hurt either!

Thanks. Yeah, I'll make sure he's got up to date system images and a recent System Restore point and a backup of the BCD.