[SOLVED] MBR partition support?

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SkyNetRising
Not true. It's very rare for motherboard to support UEFI only and not support legacy mode.
Some laptops have this.
But retail motherboards usually support both - UEFI and legacy mode. This is configurable in BIOS.

And yes - windows 10 can be installed in legacy mode too. UEFI is not a requirement.

Here example from Gigabyte Z390 BIOS screen.
To boot from MBR drive CSM support must be enabled and Storage boot option set to Legacy.

9jTUA5u.png
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RealBeast said:
Intel Z390 boards require UEFI, and thus GPT boot drives.
If you run Windows, it will have to be W10.

They allow you to create more partitions that MBR did though. And you can still use MBR drives for storage -- just not as the boot drive.
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I think I did not make my question clear. Sorry for confusion. Im trying to ask like can the OS drive be MBR partitioned? not the USB drive containing the windows iso.
 
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chenjohn274 said:
Which previous gen CPUs or motherboards support MBR?
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Any board that has drivers for Windows 7 for sure -- Z170 and some Z270 unless you use a Kaby Lake (7th Gen.) CPU, and some have a BIOS or UEFI choice.

It's the UEFI mandatory boards that requires GPT partition for the OS drive; and by extension any newer boards using Windows 10 or a newer Intel CPU (7th generation or later).

You do not need an OS drive with MBR for any particular reason though, GPT drives can handle many more partitions than MBR. Take a look at THIS.

Do you actually have a reason that you need an MBR drive for your OS?
 
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RealBeast said:
Any board that has drivers for Windows 7 for sure -- Z170 and some Z270 unless you use a Kaby Lake (7th Gen.) CPU, and some have a BIOS or UEFI choice.

It's the UEFI mandatory boards that requires GPT partition for the OS drive; and by extension any newer boards using Windows 10 or a newer Intel CPU (7th generation or later).

You do not need an OS drive with MBR for any particular reason though, GPT drives can handle many more partitions than MBR. Take a look at THIS.

Do you actually have a reason that you need an MBR drive for your OS?
Click to expand...
On the specs list, does it say if the motherboard supports ONLY UEFI, or maybe both GPT and MBR?
 
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chenjohn274 said:
ASUS PRIME B360M-A, for Windows 10 Home / Pro.
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So yes, it has a UEFI AMI BIOS just like my Z390 and only supports Windows 10. Using a GPT disk is really no big deal for your OS though. W10 will automatically create the four W10 required partitions upon install to the unallocated SSD/HDD. You can then create more partitions if you need, but it does not help performance to partition drives and folders are more efficient to organize storage since they do not have a fixed size. Your other SSDs and HDDs if any can be MBR if under 2TB and you prefer.
 
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Not true. It's very rare for motherboard to support UEFI only and not support legacy mode.
Some laptops have this.
But retail motherboards usually support both - UEFI and legacy mode. This is configurable in BIOS.

And yes - windows 10 can be installed in legacy mode too. UEFI is not a requirement.

Here example from Gigabyte Z390 BIOS screen.
To boot from MBR drive CSM support must be enabled and Storage boot option set to Legacy.

9jTUA5u.png
 
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SkyNetRising said:
Not true. It's very rare for motherboard to support UEFI only and not support legacy mode.
Some laptops have this.
But retail motherboards usually support both - UEFI and legacy mode. This is configurable in BIOS.

And yes - windows 10 can be installed in legacy mode too. UEFI is not a requirement.
Click to expand...
Look at the actual board specifications at ASUS MANUAL HERE and you will see that it only supports UEFI (and only with 8th and 9th gen Intel CPUs), and Windows 10.

Sure older boards and CPUs support both, but this is not an older board. Your statement about retail motherboards became untrue with the latest two generations of chipsets and CPUs.

There is a CSM bios setting that can help install your W10 from a non-UEFI CD or USB stick but doesn't always work real well with ASUS boards, and it only assists with the install media.

Have you built a 9th gen build yet? I've only done 6.
 
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RealBeast said:
Look at the actual board specifications at ASUS MANUAL HERE and you will see that it only supports UEFI
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And which page in the manual says that it supports UEFI only?

RealBeast said:
Sure older boards and CPUs support both, but this is not an older board. Your statement about retail motherboards became untrue with the latest two generations of chipsets and CPUs.
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I have z370 system with windows 10 in legacy mode. So ...

RealBeast said:
Have you built a 9th gen build yet? I've only done 6.
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And you were not able to install in legacy mode?
Install media must be prepared for legacy boot, it must be booted in legacy mode. Then there are no problems installing on MBR drive.
 
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SkyNetRising said:
And RealBeast - if you're downvoting my post, you obviously have no clue about the topic. 😉
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Show me that I am wrong and I will upvote you -- but you are giving out of date bad advice. The OP cannot install W10 to the ASUS PRIME B360M-A without using a GPT drive in UEFI.

That board has the same bios as the ASUS Prime Z390, which states:
"The new ASUS UEFI BIOS is a Unified Extensible Interface that complies with UEFI architecture, offering a user-friendly interface that goes beyond the traditional keyboard-only BIOS controls to enable a more flexible and convenient mouse input. You can easily navigate the new UEFI BIOS with the same smoothness as your operating system. The term “BIOS” in this user manual refers to “UEFI BIOS” unless otherwise specified"

(i.e. there is ONLY a UEFI bios). Don't be thick, go out there and find a ninth generation Intel chipset that uses a legacy bios and does not require UEFI. You obviously don't have a clue about modern motherboards. You are a couple years out of date.

**** You misunderstand the CSM setting -- that only allows non-UEFI devices to provide the boot media, that is an old CD, LAN install, or USB that is MBR -- it does not allow you to use an MBR boot disk. Learn the difference.
 
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I think that your confusion arises in the fact that CSM in older boards was used to allow W10 to be installed in a legacy mode to make it backward compatible. Unfortunately, or not depending on your viewpoint, that is no longer the case.

With modern boards that only run W10 (since the Z270 without major hacks and disabling all your USB ports -- and completely in the Z370/Z390) the CSM switch does not change the boot drive to MBR. It only allows non UEFI devices to operate during the installation to the GPT drive in order to support older peripherals that may be attached.

I had to use it with great pain when using an older GPU on a recent build. Each device attached to the UEFI board in essence needs built in UEFI instructions in its firmware. Any devices without require the use of the CSM switch, and that usually causes issues during the install due to poor implementation by the motherboard makers.
 
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RealBeast said:
**** You misunderstand the CSM setting -- that only allows non-UEFI devices to provide the boot media, that is an old CD, LAN install, or USB that is MBR -- it does not allow you to use an MBR boot disk. Learn the difference.
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UEFI BIOS doesn't automatically mean, that it can't boot into legacy mode.
It means, it can boot UEFI media in UEFI mode. But as long as it has CSM module, it can boot MBR media in legacy mode also
(hdd/ssd is boot media, if you're booting from it).

You will not find any modern motherboard with legacy BIOS. All of them are UEFI. But again - that doesn't mean, they can't boot into legacy mode. They absolutely can.

I can show screenshots later - z370 system (btw 9th gen compatible) with i7-8700 cpu and working perfectly fine in legacy mode.

You misunderstand CSM functionality yourself.
Compatibility Support Module
The Compatibility Support Module (CSM) is a component of the UEFI firmware that provides legacy BIOS compatibility by emulating a BIOS environment, allowing legacy operating systems and some option ROMs that do not support UEFI to still be used.

CSM also provides required legacy System Management Mode (SMM) functionality, called CompatibilitySmm, as an addition to features provided by the UEFI SMM. This is optional, and highly chipset and platform specific. An example of such a legacy SMM functionality is providing USB legacy support for keyboard and mouse, by emulating their classic PS/2 counterparts.
Click to expand...
 
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I accidently installed Win 10 in legacy mode on my ASUS RoG Maximus XI Hero Z390 board with a 9900K, which resulted in a Windows 10 install on an MBR disk - it was working perfectly fine, no boot issues or anything else, that would indicate a non-functional system.
I used an install USB created with Windows Media Creation Tool.

When I learned Windows 10 was running in legacy mode, I later used the process described HERE, to convert from MBR to GPT (NO reinstall needed), before rebooting and setting my BIOS from "Legacy and UEFI" to "UEFI mode only".
So as SkyNetRising has already said and proved, it can certainly be done - I just did it on accident.

I can't provide any "evidence" since my system now runs a GPT and UEFI mode setup, and everything looks like it has been that way all along.
 
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