I want to switch from BIOS to UEFI, but nothing works.

Katnax · September 17, 2021

Hello, I want to enable CSM in UEFI, I did it on my newer computer with similar specs (5800X, AsRock X570 PG mITX/TB3, WD SN750)

At the beginning, I was thinking about reinstalling windows on C, but I can't do it right now, and now I want to save as much data on all drives as possible, for precaution, I made backups of most important data from C and D drives.

I've tried mbr2gpt /validate /disk:3 (because it's my C drive M.2) and /allowfullos - it always looks like this -

PS C:\WINDOWS\system32> mbr2gpt /validate /disk:3 /allowfullos
MBR2GPT: Attempting to validate disk 3
MBR2GPT: Retrieving layout of disk
MBR2GPT: Validating layout, disk sector size is: 512 bytes
Disk layout validation failed for disk 3

When I tried desperately with AOMEI, it warned me that system partition and recovery partition are on other drives so the system might not load after reboot. (I'm not sure if it said about recovery partition, I uninstalled that program and warning was written in my native language)

Then, i wanted to create EFI partition on my M.2 drive (disk 3) I disconnected all other drives, plugged in USB with Windows 10 on it, and I tried adding that partition via diskpart. Diskpart spat out error that this drive isn't GPT. So now I'm stuck in a loop and I don't know how to convert disk 3 to GPT, and I'm kinda mad, because i recently built a new computer with slightly better specs, and it starts 5 times quicker than my main PC, because it was GPT at default and i had no trouble with CSM enabled.

I think that my D drive has system partition, because it is a clone of my first drive. So before I used SSD's, I installed systems on that drive. For some time i had 2 systems, one on that HDD and other on SSD.

What do you recommend to do? As I said, it looks like I'm stuck in a loop and I can't format C now.

My computer specs -

Ryzen 7 3700X

Asrock X570 Steel Legend

GoodRam IRDM Pro 32GB 3600Mhz (Can't get rated speeds)

M.2 HP EX920 512GB (disk C/3)

SSD Crucial MX500 1TB (disk E/0)

WD Black 2TB (disk D/1)

WD Blue 4TB (disk G/2)

XFX RX 580 8GB