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Preventing Win10 Upgrade from Writing to Clover EFI, Any Suggestions?

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I'm overdue for a major upgrade to my Win10 installation (Dual boot: Mojave on the NVMe card, Win10 on a SATA SSD), but due to my slow internet, it's more convenient for me to do a "upgrade in place" with the Win10 installer ISO downloaded elsewhere. The problem is I want to avoid some problems that I had experienced with my previous Hackintosh (Yosemite and Win7 on separate HDDs).

I want to prevent Win10 writing to the EFI on the OSX drive; the Win7 installer put the Microsoft EFI on the OSX drive instead of the Windows drive. It didn't affect the booting of either, but it made the Windows drive dependent on presence of the OSX drive. Also the presence of other SATA storage devices caused problems with the installer.

I'd like to try the upgrade without physically removing the NVMe card or disconnecting SATA storage devices, because I would need to unplug all the cables in the back, pull the tower off the desk, unplug the SATA cables, remove the video card blocking the M.2 slot.

So my plan is to:

  1. Disable all the unneeded SATA ports in BIOS.
  2. Remove NVMe drive from the boot order in BIOS, booting directly off the Win10 drive.
  3. Before running the Win10 installer, I'll use device manager to disable the NVMe.
Is there something else I can do to make sure Win10 avoids writing to the drive containing OSX/Clover?
 

Feartech

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I'm overdue for a major upgrade to my Win10 installation (Dual boot: Mojave on the NVMe card, Win10 on a SATA SSD), but due to my slow internet, it's more convenient for me to do a "upgrade in place" with the Win10 installer ISO downloaded elsewhere. The problem is I want to avoid some problems that I had experienced with my previous Hackintosh (Yosemite and Win7 on separate HDDs).

I want to prevent Win10 writing to the EFI on the OSX drive; the Win7 installer put the Microsoft EFI on the OSX drive instead of the Windows drive. It didn't affect the booting of either, but it made the Windows drive dependent on presence of the OSX drive. Also the presence of other SATA storage devices caused problems with the installer.

I'd like to try the upgrade without physically removing the NVMe card or disconnecting SATA storage devices, because I would need to unplug all the cables in the back, pull the tower off the desk, unplug the SATA cables, remove the video card blocking the M.2 slot.

So my plan is to:

  1. Disable all the unneeded SATA ports in BIOS.
  2. Remove NVMe drive from the boot order in BIOS, booting directly off the Win10 drive.
  3. Before running the Win10 installer, I'll use device manager to disable the NVMe.
Is there something else I can do to make sure Win10 avoids writing to the drive containing OSX/Clover?
should be fine to disable it in bios

but would be best to actually remove the drive
 
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should be fine to disable it in bios

but would be best to actually remove the drive

I don't think I can disable the M.2 slot in BIOS; I couldn't find an option for that. The best I can do is remove from the boot list and disable it in Windows device manager. I'm just lazy :)... I'm in a tight space, so I can't work on the computer without moving it off the desk.
 

Feartech

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I don't think I can disable the M.2 slot in BIOS; I couldn't find an option for that. The best I can do is remove from the boot list and disable it in Windows device manager. I'm just lazy :)... I'm in a tight space, so I can't work on the computer without moving it off the desk.
best to remove it for better results, don't be lazy
 
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best to remove it for better results, don't be lazy

I was hoping somebody might know a method other than the obvious. I would be nice if Windows just installed its EFI on its own drive, but past experience has proven otherwise. Oh well... I had to at least ask :)
 

Jamesbond007

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I was hoping somebody might know a method other than the obvious. I would be nice if Windows just installed its EFI on its own drive, but past experience has proven otherwise. Oh well... I had to at least ask :)
Yes, you can't disable the M.2 slot in the BIOS. At least I have never seen such an option in the motherboards I have used. So you have no choice but to temporarily remove the M.2 drive before upgrading Windows 10.
 

Going Bald

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If you make the Win10 drive first in BBS boot order and the NVMe drive last, disabling the other SATA ports with drives connected you should not have a problem with it. Windows only writes to other drives if they are listed before the Windows drive in the BBS order. If there is already an EFI partition on the Win10 drive the new installation will use it.
Suggest using this procedure
 
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I second the don't be lazy sentiment as being the safest route.

That said, as long as the Windows drive is first in the boot order, performing an in-place upgrade of Windows should work as expected, and use the existing EFI partition on the same drive.

If upgrading from Windows 7 to 8/8.1/10 then it doesn't work out that way (as you discovered). This is because Windows 7 installs using MBR boot - no EFI partition is created. All available space on the drive had been allocated, so Windows 10 had no choice but to use the first available EFI partition, which happened to be on your NVMe drive. Why? Simply, because it was there!

If you have any doubts, then first removing all of the other drives remains the most trouble-free solution - All it takes is a screwdriver and your time.
 
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Thanks everyone for all your suggestions. I had a little extra free time, so I decided to just go ahead and pull the NVMe out and disable the unnecessary SATA ports in BIOS. Upgrade in Place went without any issues.

Turns out I didn't need to remove my video card after all. I used the M.2 slot near the CPU, not the one underneath the video card. There was enough clearance to remove it without unplugging anything inside.
 
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