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peopol

UEFI or UEFI+LEGACY for win 10 instlalation?

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Posted · Original PosterOP

Probably a dumb question, i'm currently installing win 10 on ssd with legacy+uefi. It's preparing files for installation but it's doing it so slow. Did i mess up by picking that bios setting, or can i switch it later without any problems?

Side note: it had (has?) windows 10 on it from my previous pc i was planning on formating it.

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Last time I let the mobo picked legacy + uefi then install Windows, Windows modified my SSD to be compatible with legacy mode only, and when I tried to enable UEFI only in BIOS, Mobo couldn't detect my ssd at all. Legacy + UEFI extend post time too. 

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UEFI only, so that windows 10 would install in UEFI mode and you’ll get secure boot, HDD >2TB support, faster post time and more 

 

Legacy install, installs windows using MBR partition type with is useful for old systems which does not support UEFI and it doesn’t support secure boot and partition more than 2TB as it’s using the MBR partition type(UEFI uses the GPT partition type )

 

 

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UEFI only.

Also make sure that CSM (Compatibly Support Module) is disabled, if you have that option.

 

Legacy, if if you plan to install old OSs, like Windows 7 or earlier, or you have a very old hardware that you still want to use and causes issue with the system being in UEFI.

 

Another note: If you boot from a USB flash drive to install Windows (or any other OS that is UEFI compatible), if you have the option to pick "UEFI: <USB flash drive name>", and "<USB flash drive name>", pick the one that starts with UEFI.

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On 1/11/2020 at 6:14 PM, peopol said:

Probably a dumb question, i'm currently installing win 10 on ssd with legacy+uefi. It's preparing files for installation but it's doing it so slow. Did i mess up by picking that bios setting, or can i switch it later without any problems?

Side note: it had (has?) windows 10 on it from my previous pc i was planning on formating it.

You can:

1. Boot your old win10 (on new hardware) and check if it's uefi or legacy (you may check this by booting old system in UEFI only mode - if system start booting - your current Windows installation is already in UEFI mode). Windows installer may have problem with Windows UEFI installation if drive is MBR formatted (or Legacy if drive has GPT).

2. If you have legacy installation (MBR), you can easily convert it using mbr2gpt tool that is included in Win10 (you can find many tutorials how to do that). Or leave it as is.

3. If you want to install Win10 again for some reason - the best way to change drive from MBR to GPT is to use some nice partition manager like MiniTool Partition Manager.

 

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17 hours ago, homeap5 said:

2. If you have legacy installation (MBR), you can easily convert it using mbr2gpt tool that is included in Win10 (you can find many tutorials how to do that). Or leave it as is.

Any idea how to convert an install from MBR type to UEFI(GPT)? when I try MBR2GPT/validate it tells me that it isn't eligible... did this in WINRE, CSM is on to boot into winre

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2 minutes ago, Yongtjunkit said:

Any idea how to convert an install from MBR type to UEFI(GPT)? when I try MBR2GPT/validate it tells me that it isn't eligible... did this in WINRE, CSM is on to boot into winre

Do you choose correct disk?

https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10

 

And do you check is your drive MBR? If it's already GPT then you have UEFI installation and no conversion is required.

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1 minute ago, homeap5 said:

Do you choose correct disk?

https://www.windowscentral.com/how-convert-mbr-disk-gpt-move-bios-uefi-windows-10

 

And do you check is your drive MBR? If it's already GPT then you have UEFI installation and no conversion is required.

I didn't select the disk, I let it choose it by itself since there's only 1 disk in the system

 

Yup, verified that it can't boot with CSM disabled 

 

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50 minutes ago, Yongtjunkit said:

I didn't select the disk, I let it choose it by itself since there's only 1 disk in the system

 

Yup, verified that it can't boot with CSM disabled 

 

Not really, USB you're using for boot is disk too.

 

Just follow that link I gave you or stay with legacy boot . There is no big difference anyway. If your system boots then just use it.

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14 hours ago, homeap5 said:

Not really, USB you're using for boot is disk too.

 

Just follow that link I gave you or stay with legacy boot . There is no big difference anyway. If your system boots then just use it.

I've just tried it in a VM and it bricks windows(eventhough it says it's eligible, switched between UEFI and BIOS on VMware and I got nothing), so I guess on a real system I would recomend a clean install to install more than 2TB of HDD, UEFI, fast boot, secure boot then.....

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5 hours ago, Yongtjunkit said:

I've just tried it in a VM and it bricks windows(eventhough it says it's eligible, switched between UEFI and BIOS on VMware and I got nothing), so I guess on a real system I would recomend a clean install to install more than 2TB of HDD, UEFI, fast boot, secure boot then.....

I converted few real systems using mbr2gpt without any issue. Even one with single partition (boot partition moved into system partition).

 

But of course it's up to you how do you made it.

 

What is wrong with legacy boot? 3 seconds slower boot?

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23 minutes ago, homeap5 said:

I converted few real systems using mbr2gpt without any issue. Even one with single partition (boot partition moved into system partition).

 

But of course it's up to you how do you made it.

 

What is wrong with legacy boot? 3 seconds slower boot?

I've used MBR2GPT /validate to make sure that it meet the requirement then I use MBR2GPT /convert to convert to GPT partition but it won't boot in both legacy and uefi 

 

not really, would prefer UEFI due to more than 2 TB support, Secure boot 

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18 minutes ago, Yongtjunkit said:

I've used MBR2GPT /validate to make sure that it meet the requirement then I use MBR2GPT /convert to convert to GPT partition but it won't boot in both legacy and uefi 

 

not really, would prefer UEFI due to more than 2 TB support, Secure boot 

This limitation is only for boot drive. If your boot drive is smaller than 2TB, you can have legacy boot and still use drives (other than boot) larger than 2TB with GPT partition table.

 

And secure boot may work or not - depends on hardware. No real benefits of using it.

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