Which is better for non UEFI boot? MBR or GPT?

My laptop came with Windows 8.1 in UEFI mode/GPT partitions

which is better if I am gonna install Windows 7 where I have to choose Legacy Boot ROM so I think it won't be UEFI then right?

is it better to go for GPT or MBR?

Mind you, I have two 1 TB Samsung 840 EVO SSDs so having support for 3TB+ partitions means nothing to me. but any other benefits of GPT over MBR?

 

Advantages of GPT

• Support for larger capacity drives.
• Supports more visible primary partitions.
• Slightly faster boot times (shorter BIOS POST)
• Interaction with BIOS variables.
• Secureboot*

*IMO Secureboot is a false sense of security so personally I would not see that as an advantage.


Advantages of MBR

• Better compatibility.

You should be able to install W7 with UEFI using CSM to GPT then once installed with updated drivers and W8 bootmgr go full UEFI (no CSM) with added BCD option if wanted. GPT can have bootmgr issues, especially when adding disks, and may not play well with older 3rd party disk utilities.

A few factors such as whether you want to keep W8 too and dual boot. You'll have to decide what is best for you. One man's gravy is another man's poison .

 

I will go with MBR for better compatibility and no real advantage until 3TB partition...

 

wait correct me if I'm wrong. but even if I install Windows 7 then disable CSM (aka legacy boot ROM) the Windows would not go past the Windows screen loading image

and no I will not be dual booting

can you tell me if there is a trick to get full UEFI boot in Windows 7 for my Alienware 18?

thanks a lot man!!! your post made me disable CMS after I have installed Windows 7 and it booted just fine!!! it seems that it cannot boot without CMS only fir the Windows 7 installer but once installed I can now boot in UEFI mode with no CMS

 

Check if that is the case with HE. If you check under option ROMs which are legacy it should be totally blank.

For it to work on my systems it needs to be installed with CSM then video driver updated as the native W7 does not seem to handle the EFI framebuffer, with BCD novesa option set to yes and use of W8 EFI boot manager on the EFI system partition.

FWIW secureboot does not work with W7. Also it's possible to boot a GPT system disk on a legacy board if you have a second disk with MBR, needed to do that once on an older legacy BIOS P45 board where the OS was on a RAID0 with GPT partitioning.

 

Bummer....it seems UEFI with no Legacy boot options works only if I set my laptop on the Intel HD Graphics 4600, but if I switch to the nVIDIA GeForce GTX770M, it won't get past the Windows splash screen. I can hear the noise of the Windows startup and can see my external HDD initializing through its activity LEDs but the screen would be stuck on the black splash screen What gives!

 

Did you set the option

BCDEdit /set {current} novesa yes

from your W7 OS before switching to discrete?

 

sorry mate, I'm a n00b!e, can you please tell me step by step how to do that?

cheers

 

There's no reason to use GPT in your case.

 

I would say the support for larger drives then 3tb would be the biggest reason to have GPT.

That is up for debate....aka

the MBR is the only place that holds the partition information. If it ever get corrupted (and yes, it can get corrupted very easily), the entire hard disk is unreadable.

Not sure about you but I had no problems with GPT but I didn't make them boot drives. Your boot drive doesn't have to be a 3tb Desktop if you need more then that then get a laptop that has two drive bay and put the larger drive in the second slot and a smaller for the boot so should the boot fail then you still have your information secured in the second drive.

 

Open up a command (cmd) box with admin priviledge and enter "BCDEdit /set {current} novesa yes". You can run cmd box in admin mode by right clicking it and select run as admin.

@SormJumper, if you corrupt your GPT protective MBR what happens? MBR takes up only one sector and should be backed up as with anything else on the disk however it is easy enough to rebuild if the partitioning scheme is understood. Note that there are a lot of external drives that are >2TB and use MBR partitioning. Thanks to 4k sectors size limit is increased to 16TiB. There are still many older systems and 32-bit ones that would not be able to read GPT.

 

This doesn't compute either you have GPT or MBR??? I don't think you can have both format on the same drive.

Then it would be time to consider data migration to a more up to date O/S as data will increase in storage needs and you will need more space to store it. And for 32bit XP and 32bit Windows 2003 from wiki doesn't support GPT drives or as boot drive but their x64 versions XP can't boot but Windows 2003 can boot from GPT drive.

aka

GUID Partition Table - Wikipedia, the free encyclopedia

 

In fact, it computes perfectly. Dufus knows what he is talking about here:

The GPT table has as its first entry a so-called Protective MBR (also called Legacy MBR), which is a phony MBR designed to protect the disk from legacy programs that do not understand GPT. It makes the entire disk appear (to such legacy programs) as one big partition of unknown type.

That Wikipedia article shows it very clearly in this illustration and explains it in this section.

Don't worry about it. Happens all the time

In response to Dufus' question, I would assume that corrupting the Protective MBR is by no means fatal, and probably doesn't even affect normal operation of a GPT compatible OS and programs. It should be a simple matter to repair. I have not tried it, though.

 

did that, didn't help, still cannot see the desktop if I am on the nVIDIA Graphics, only on the Intel HD Graphics would it boot to the desktop

 

@Double Helix Are you using switchable graphics or a muxed system that allows disabling of the iGD? If you are using the W8 firmware boot manager in the EFI system partition and the bcdedit fix and have installed the latest graphics drivers for your discrete card as well as the integrated ones under CSM previously then I can only assume the VBIOS of the discrete card may incompatible. Might just to have make do with CSM if that is the case.

If that were only the case hybrid booting would be a walk in the park. Tried that early on when GPT was introduced and no go however it is very easy to change the first sector with a GPT disk so it becomes legacy boot. Just need to fill the partion table with the relevant partitions of interest and some basic loader code.

As for protective MBR corruption, a lot will depend on the BIOS but as an example if the signature is missing some BIOS may stop there, those that ignore it and attempt to boot Windows will result in a BSOD. On a non OS drive it will be recognized by Windows as a non-initialized disk, no data.

If the protective table entry is corrupt likely BIOS will not recognize it as GPT and hence not bootable.


No need to take my word for it, people are welcome to try for themselves, just make sure you can fix it. If you understand the schemes it is very easy to fix or simply be able to restore a backup of the first sector. If not able then better leave it alone.

 

That surprises me. I would have thought the Protective MBR would be ignored, since it has no bearing on the actual GPT table or the partitions themselves. I suppose BIOS uses it as a signature, and sees changes as evidence of tampering or corruption. Still, being unable to boot because of it is a bit like a car refusing to start because the MagicTree air freshener is missing

Again, I haven't tried it myself, but I do believe you.

Anyways, back on topic.

@Double Helix: As Dufus pointed out, your Video BIOS may not be UEFI/GPT compatible. As others have stated, you do not really need UEFI. It is only required if you have to boot from a >3TB drive. I would say staying in legacy BIOS mode (CSM) sounds like the simple choice in your case. You can still read/write GPT data disks of any size.

 

Negative, it is, because in Windows 8.1 it works just fine. Only when I want to install 7, I have to enable Legacy ROM which I hate since it slows down my startup drastically

please help meh

 

Other than what was mentioned above I have nothing to suggest.

Here's part of my BCD settings for the laptop.

Code:

identifier              {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
device                  partition=C:
path                    \Windows\system32\winload.efi
description             Windows 7 Home Premium
locale                  en-US
testsigning             Yes
osdevice                partition=C:
systemroot              \Windows
resumeobject            {xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx}
bootmenupolicy          Legacy
novesa                  Yes
useplatformclock        Yes

Note however I dual boot on the laptop but works fine on the desktop with just W7 and discrete graphics updated with GOP. The laptop is muxless so everything goes through the iGD so always on. The discrete card GTX 765m has no GOP.

Have you installed the latest graphics driver?