Windows 10 drive rendered inoperable during OSX 10.15.4 Upgrade

[Going Bald]

Ok, have been poking around the BIOS for the best part of an hour & still no Joy getting windows to boot again (although at least nothing I change seems stop OSX booting which is great)

My Motherboard (MSI z270 SLI Plus) doesn't seem to have any obvious 'CSM on/off' setting, but does have 'Legacy+UEFI' boot mode select. This is always been on. There is also a dedicated 'Windows 8.1/10" switch...this is usually off, but when its 'on' I can only use UEFI boot mode..I have tried every combination of these & still no joy from Windows. Sometime though I get a tiny square windows logo stuck at the centre of the screen....sometimes the flashing cursor....
..ive also tried booting via the Clover USB with these settings & it makes no difference

..the mystery to me is why Windows10 has been booting ok these last few months...any more thoughts ? & if I *do* have to just wipe it & reinstall Win10, I don't remember the install USB stick ever giving me a choice of installing a 'EFI Partition'...it just asked if I wanted to install or not...are there deeper options?

change the Legacy + UEFI mode to UEFI only and set the OS to Windows8.1/10 instead of Other OS, then install Win10.

 

[RuC2020]

change the Legacy + UEFI mode to UEFI only and set the OS to Windows8.1/10 instead of Other OS, then install Win10.

Ok cool. So do a full re-install of windows on that SSD with the above settings & I should be able to Dual-boot again yeah? So I guess I'm learning from this, that Windows does a different kind of install based on the BIOS settings it sees? Most interesting.

Any ideas why it was working before in that case? Thats the strange bit

 

[umuur]

Ok cool. So do a full re-install of windows on that SSD with the above settings & I should be able to Dual-boot again yeah? So I guess I'm learning from this, that Windows does a different kind of install based on the BIOS settings it sees? Most interesting.

Any ideas why it was working before in that case? Thats the strange bit

Hi there, I have very similar specs with you. How did you run HD 630 iGPU with MSI z270 SLI Plus. Could you please share your config?

 

[RuC2020]

Hi there, I have very similar specs with you. How did you run HD 630 iGPU with MSI z270 SLI Plus. Could you please share your config?

I'm not using the inbuilt Graphics, but a Radeon RX580

These were my BIOS settings


MSI Z270 Carbon BIOS Settings

1. Save & Exit → Restore Defaults : Yes
2. Advanced \ Integrated Peripherals → Network Stack : [Disabled]
3. Advanced \Integrated Peripherals → Intel Serial IO : [Disabled]
4. Advanced \ USB Configuration → XHCI Hand-off : [Enabled]
5. Advanced \ USB Configuration → Legacy USB Support : [Auto]
6. Advanced \ Windows OS Configuration → MSI Fast Boot : [Disabled]
7. Advanced \ Windows OS Configuration → Fast Boot : [Disabled]
8. Overclocking → Extreme Memory Profile(X.M.P) : [Enabled]
9. Overclocking \ CPU Features → Intel Virtualization Tech : [Enabled]
10. Overclocking \ CPU Features → Intel VT-D Tech : [Disabled]
11. Boot → Boot mode select : [UEFI]

Based on the GPU you’re using change the following settings:

Dedicated graphics card:

1. Advanced \ Integrated Graphics Configuration → Initiate Graphic Adapter : PEG

Intel iGPU:

1. Advanced \ Integrated Graphics Configuration → Initiate Graphic Adapter : IGD
2. Advanced \ Integrated Graphics Configuration → DVMT Pre-Allocated : 96M

(Optional) Wake hackintosh from sleep thru Input:

1. Advanced \ Wake Up Event Setup → Resume By USB Device : [Enabled]
2. Advanced \ Wake Up Event Setup → Resume From S3/S4/S5 by PS/2 Mouse : [Enabled]
3. Advanced \ Wake Up Event Setup → Resume From S3/S4/S5 by PS/2 Mouse : [Enabled]