Windows 10: What is the command to change UEFI to Legacy?

Hello, Microsoft! Recently, I’ve changed my BIOS settings from Legacy to UEFI via commands.. After I restarted the computer it had an error that it didn’t find the hard drive on the computer. I got a flash drive with Windows 10 Installation media on it, but it says that this pc cannot install Windows 10… So I went to the Recovery thing via the flash drive. I got into the administrator command prompt, but it says Administrator: X:\windows\SYSTEM32\cmd.exe I don’t know if the X is normal, beacuse normally it’s C. Anyway, I didn’t find the command to change from UEFI to Legacy again.. They sa

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Legacy to UEFI

I'm debating moving to UEFI form my now legacy BIOS (Award Software Int.) the mother board is a GA-Z68XP-UD3 rev1.0 on the the following link it shows a UEFI BIOS U1J )UEFI BIOS)

https://www.gigabyte.com/Motherboard/GA-Z68XP-UD3-rev-10#support-dl-bios

Currently I'm running the legacy F10 BIOS. Does installing the UEFI BIOS automatically take care of everything to get to the UEFI BIOS? Installing the UEFI BIOS following the instructions using the Q-flash method GIGABYTE How to Reflash Motherboard BIOS

What's steps do I take and in what order?

Much appreciated

 

Quick UEFI/Legacy question

I have had Hawaii cards and Fiji cards with UEFI roms, used 1 at a time on an Asus P5K Premium motherboard LGA 775 with Q6600 without an issue. AMD ROMs are Hybrid ROMs ie have a legacy section with UEFI module, so you won't have an issue with card which has UEFI ROM on legacy system. The legacy sytem will just ignore the UEFI module in vbios.

To make Windows show UEFI as bios mode you need your Z97 Pro Gamer in "Pure UEFI" mode (ie CSM = OFF). Windows IIRC only changes between legacy / UEFI on install, so even if you change to CSM=Off it may not show UEFI bios mode in Windows system info tool. I have not had 2 GPUs in a system at one time, even if I had them, I thought my PSU was not up to the job, so can not comment if only the primary display card requires UEFI module and it is irrelevant if secondary GPU does not.

If you get black screen/issue after setting CSM off then remove the card with legacy ROM, if mobo boots then you'll know you need to update the ROM on that card.

 

Most Drives disappear when disselecting "Legacy + UEFI". Do i need to reinstall windows?

Hi, I’m Nicole, I’ll be happy to help you out today.

The first method will need to reinstall Windows after converting the drive from MBR to GPT so it can work in UEFI mode. Here are the steps.

1. After you convert Legacy BIOS to UEFI boot mode, you can boot your computer from a Windows installation disk.

2. At the Windows Setup screen, press Shift + F10 to open a command prompt.

3. Type “diskpart” and use the command “list disk-> select disk #-> clean->convert gpt” to convert the disk from MBR to GPT. On select disk, select your m.2 drive number.

4. Now, you can go back and reinstall Windows. If you try to install Windows without these steps, you will get the error “Windows cannot be installed to this disk” after you change BIOS to UEFI mode.

The second method is changing the boot mode from Legacy to UEFI without reinstalling Windows but you may need to use a 3rd party application. You can follow this link.

https://www.diskpart.com/gpt-mbr/change-legacy-...

Update me on this issue.

Thank you.