[SOLVED] Help with moving from Legacy BIOS to UEFI

[spektro]

Windows 10 installer detects Samsung PM871 M.2 SSD only in Legacy Bios Mode. How can I switch to UEFI?

I have bought preowned Dell Precision 5820. It came with Samsung's PM871 M.2 SSD, P/N: MZVLB512HAJQ. It had Windows 10 installed in Legacy BIOS mode. I wanted to upgrade to UEFI, but windows installer doesn't see the drive. I cleaned it in Diskpart and updated UEFI FW, without success.
However when booted in Legacy BIOS Windows installer sees the drive.
Is there any way to make Windows install in UEFI mode?

 

[Lutfij]

Welcome to the forums, newcomer!

Can you check and see which BIOS version you're currently on? You will need to enable AHCI in storage controller as well as turn off Secure Boot option in BIOS. You might want to remove the CMOS battery from the ssytem(while it's powered down and disconnected from the wall) and replace it after 15 minutes to see if you can enable UEFI mode and then proceed to install the OS.

Speaking of which, did you fabricate your bootable installer using Windows Media Creation Tools?

 

[spektro]

I'm on 2.4.0, I was on 1.9.4. Secure boot was off all the time, and AHCI was on.
I restored defaults.
I can enable UEFI.
USB was made with Rufus. It always worked for me.
The problem is Windows installer sees the drive only when booted in legacy mode.
BIOS recognizes the drive in both modes.

 

[ex_bubblehead]

Use the Windows Media Creation Tool to build a new image on the USB stick. Rufus likely didn't create a UEFI compatible version. The Microsoft tool creates an image that works both ways.

 

[rocktalkrock]

I'm on 2.4.0, I was on 1.9.4. Secure boot was off all the time, and AHCI was on.
I restored defaults.
I can enable UEFI.
USB was made with Rufus. It always worked for me.
The problem is Windows installer sees the drive only when booted in legacy mode.
BIOS recognizes the drive in both modes.

Is your SSD formatted to MBR or GPT? If it's MBR, try converting the drive to GPT.