Question Pc only boots with multiple HDD's connected after BIOS update

Jun 19, 2022
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I recently upgraded my PC. This required a BIOS update, 1404 to 4403, (Asus tuf gaming x570 plus) after which my computer no longer recognized my SSD boot drive unless I enabled CSM in BIOS.

After I was able to boot it looks like my boot drive was made up of multiple HDD's, which I use as storage, as well as my SSD.

Is there any way to fix this? Preferably without reloading Windows 10

 
Is there any way to fix this? Preferably without reloading Windows 10
Bootloader is located on 2TB drive (500MB partition with "System, Active" in description).
Without this drive connected, you can't boot into windows.

OS on your pc is installed in legacy mode.
You never were able to boot into windows without CSM enabled.

You could make bootloader on drive containing windows OS partition.
Then 2TB drive would not be necessary for booting into windows.
Execute following from elevated command prompt. Regular command prompt will give error on last step.
(if you get any errors, then stop immediately)
diskpart
list disk
select disk 3
list partition
select partition 1
(select 465GB partition)​
shrink desired=500
create partition primary
format fs=ntfs quick
active
assign letter=H
exit
bcdboot c:\windows /s H:

Last message should be "Boot files created successfully".
If all went good, then
boot into BIOS and
change boot priority, so 500GB drive is 1st in boot order.

 
Jun 19, 2022
4
0
10
0
Bootloader is located on 2TB drive (500MB partition with "System, Active" in description).
Without this drive connected, you can't boot into windows.

OS on your pc is installed in legacy mode.
You never were able to boot into windows without CSM enabled.

You could make bootloader on drive containing windows OS partition.
Then 2TB drive would not be necessary for booting into windows.
Execute following from elevated command prompt. Regular command prompt will give error on last step.
(if you get any errors, then stop immediately)
diskpart
list disk
select disk 3
list partition
select partition 1
(select 465GB partition)​
shrink desired=500
create partition primary
format fs=ntfs quick
active
assign letter=H
exit
bcdboot c:\windows /s H:

Last message should be "Boot files created successfully".
If all went good, then
boot into BIOS and
change boot priority, so 500GB drive is 1st in boot order.

So possibly a dumb question but how do I change the boot priority so the 500 GB drive is 1st in boot order? The 500 GB drive, at least when CSM is enabled, is the only drive that would show up as a possibility. Can I disable CSM now?
 
how do I change the boot priority so the 500 GB drive is 1st in boot order?
The 500 GB drive, at least when CSM is enabled, is the only drive that would show up as a possibility.
Go into BIOS boot priority settings and change accordingly.
Also check HDD BBS settings.
If you can't figure it out, then show screenshots from BIOS screens.
Can I disable CSM now?
No, you can not.
Windows is installed in legacy mode. If you disable CSM, system becomes unbootable.
 
Jun 19, 2022
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Go into BIOS boot priority settings and change accordingly.
Also check HDD BBS settings.
If you can't figure it out, then show screenshots from BIOS screens.
Here is what I have for a boot priority in BIOS




Even Boot menu just gives me this:





No, you can not.
Windows is installed in legacy mode. If you disable CSM, system becomes unbootable.
Should I use MBR2GPT to make it not legacy then?
 
Jun 19, 2022
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Does your system boot properly into windows with 500GB drive as 1st in boot priority?
Show result of your progress - screenshot from Disk Management.

If you did all the instructions correctly, then to convert to UEFI, you'd have to use mbr2gpt utility.
Here is my current disk management is:



I think that it boots fine now from 500GB drive as 1st in boot priority, but I have not tested by disconnecting the other drive to make sure though I have been getting errors in Event Viewer

 

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