How do you change BIOS from legacy to UEFI mode?

[Seanzky]

So I closed my SSD to my NVMe and even though my NVMe was supposed to be GPT, because my SSD (Win 10 OS) had MBR, it converted the NVMe to MBR. I tried using the mbr2gpt tool in windows\system32 but kept getting an error. After looking deeper into it, I realized it was because my BIOS mode was in legacy (verified in System Information). How do I change this without reinstalling Windows 10 from a USB? I already changed in my motherboard's BIOS from legacy to UEFI but this doesn't seem to affect the BIOS mode in Windows. I'm pretty sure this is all that's preventing me from converting my NVMe from MBR to GPT.

[AnonymousGuy]

You can't change from legacy to UEFI without reinstalling Windows. 

[pyrojoe34]

You will have to re-install Windows. At this point, unless you have a very specific reason for doing so, you should be using UEFI anyway.

[Sniperfox47]

12 minutes ago, AnonymousGuy said:

You can't change from legacy to UEFI without reinstalling Windows. 

You absolutely can. It's just a PITA.

 

15 minutes ago, Seanzky said:

After looking deeper into it, I realized it was because my BIOS mode was in legacy (verified in System Information). How do I change this without reinstalling Windows 10 from a USB? I already changed in my motherboard's BIOS from legacy to UEFI but this doesn't seem to affect the BIOS mode in Windows. I'm pretty sure this is all that's preventing me from converting my NVMe from MBR to GPT.

It's really not worth the headaches to fix everything when you try to convert and it all breaks. Just back everything up and reinstall. It's less work to just reinstall Windows. Just make sure UEFI boot mode is enabled in your UEFI config ("BIOS" menu) before installing.

 

If you really really really really want to fight with it and convert because ¯\_(ツ)_/¯, then you'll need to make sure you've got UEFI boot enabled, get an original install/repair disk/USB-drive for your OS, rebuild your bootloader, then reboot back into the restore media and do an offline system file check and dism repair. And then go through and fix anything that winds up broken.

[Sniperfox47]

Oh oops. Forgot. You need a Linux based repair USB or liveusb as well, since you can't make a bootable EFI system partition on an MBR drive inside Windows or Windows RE for some reason >.>

[Seanzky]

40 minutes ago, ImHyperstyle said:

1. Completely shut down your computer.
2. Power on the system. As soon as the first logo screen appears, immediately press F2 to enter the BIOS.
3. Use the right arrow key to select Boot.
4. With Boot Mode highlighted, press Enter, and then use the down arrow to select Legacy BIOS.
5. Press Enter.
6. Press F10, and select Yes to save the change and exit the BIOS.

It's a little confusing and not as simple for my motherboard, but I've already done this.

 

I have an ASRock Z270 Fatal1ty Gaming K4.

[Seanzky]

44 minutes ago, Sniperfox47 said:

You absolutely can. It's just a PITA.

 

It's really not worth the headaches to fix everything when you try to convert and it all breaks. Just back everything up and reinstall. It's less work to just reinstall Windows. Just make sure UEFI boot mode is enabled in your UEFI config ("BIOS" menu) before installing.

 

If you really really really really want to fight with it and convert because ¯\_(ツ)_/¯, then you'll need to make sure you've got UEFI boot enabled, get an original install/repair disk/USB-drive for your OS, rebuild your bootloader, then reboot back into the restore media and do an offline system file check and dism repair. And then go through and fix anything that winds up broken.

I really wish I had done this but it never crossed my mind for some reason when I was reinstalling Windows 10. The thing is that when I installed Windows, I didn't use an online account. Unless I installed Windows using an online account, Microsoft just gobbles up the legit license I have. This already happened and I am on my second legit Windows license. I couldn't reuse my first license because it wasn't linked to an online account. The license I'm using now is my last one.

[Sniperfox47]

1 minute ago, Seanzky said:

I really wish I had done this but it never crossed my mind for some reason when I was reinstalling Windows 10. The thing is that when I installed Windows, I didn't use an online account. Unless I installed Windows using an online account, Microsoft just gobbles up the legit license I have. This already and I am on my second legit Windows license. I couldn't reuse my first license because it wasn't linked to an online account. The license I'm using now is my last one.

As long as you don't change the motherboard you should be able to just reinstall Windows 10, skipping the step of putting in a license, and when you first connect to the internet it should reactivate. I don't have a Microsoft Account on my desktop either and I haven't had an issue yet.

 

Worst case, as long as it's been used to upgrade in the past you can use your Windows 7 license key to activate Windows 10.

[Seanzky]

5 minutes ago, Sniperfox47 said:

As long as you don't change the motherboard you should be able to just reinstall Windows 10, skipping the step of putting in a license, and when you first connect to the internet it should reactivate. I don't have a Microsoft Account on my desktop either and I haven't had an issue yet.

 

Worst case, as long as it's been used to upgrade in the past you can use your Windows 7 license key to activate Windows 10.

Ah! Good point! I did change motherboards and I do remember reading something about that in their knowledge base. Thanks. I just might do that then. As for using Windows 7 license in Windows 10, that's what my second license is. Haha. I was ready to spend and buy another Windows 10 but after trying my legit Windows 7 Home Premium key, which I bought for my laptop that has since been converted to Linux, it worked and allowed to be activated.

 

Sigh. The only painful part now is not reinstalling everything but the massive game library and the time it will take to download. I also have to write that ISO to a USB stick again because I'm pretty sure I've reformatted that thing since.

 

But thank you so much again for reminding me about the motherboard thing!

[Sniperfox47]

13 minutes ago, Seanzky said:

Sigh. The only painful part now is not reinstalling everything but the massive game library and the time it will take to download.

If it's a steam library, just copy it to a backup drive and then copy it back when you're done. Assuming you still have your old SSD. Steam will handle setting up registry keys and game folders and everything for you when you're back up.

[Seanzky]

12 minutes ago, Sniperfox47 said:

If it's a steam library, just copy it to a backup drive and then copy it back when you're done. Assuming you still have your old SSD. Steam will handle setting up registry keys and game folders and everything for you when you're back up.

I already have that set up actually. I do have my 850 EVO with my games in it. Good point. Forgot about that. Is there a way to just factory reset Windows 10 with the option to use GPT instead of MBR or do I have to do a reformat and start from scratch? Right now my 960 EVO is the only MBR and my 850 EVO and Seagate 4TB are both GPT. My motherboard is already in UEFI mode just that my boot drive (NVMe) is still on MBR because Windows was installed using legacy. *sigh*

[Sniperfox47]

Just now, Seanzky said:

I already have that set up actually. I do have my 850 EVO with my games in it. Good point. Forgot about that. Is there a way to just factory reset Windows 10 with the option to use GPT instead of MBR or do I have to do a reformat and start from scratch? Right now my 960 EVO is the only MBR and my 850 EVO and Seagate 4TB are both GPT. My motherboard is already in UEFI mode just that my boot drive (NVMe) is still on MBR because Windows was installed using legacy. *sigh*

Nah. The only way to convert is to do it the hard manual way. It's not officially supported by Microsoft in any way shape or form.

 

Reinstalling Windows is by far the easiest and fastest way. Sorry.

[Seanzky]

Thanks again for all your help @Sniperfox47 and everyone else that tried. I finished everything last night and I got to keep my Windows license as well as be in UEFI mode.