0

So as of right now I have a PC with a BIOS-only mainboard (Gigabyte 775 - GA-P35-DS3) with which I installed Windows 10 64bit on my 4TB hard drive with MBR.

Now I'd like to buy a new mainboard with UEFI and convert this system hard drive from MBR to GPT without data loss to make use of the whole 4TB storage (as a single partition).

According to Google it's possible to convert an HDD from MBR to GPT without data loss. But I'm not so sure if that also goes for system drives which were installed with a BIOS mainboard.

So is it possible? Are there any special things I need to do (or watch out for) to get this working? Or can I simply do a backup, build in my new mainboard and use one of the many MBR-to-GPT conversion-programs?

Improve this question
4
  • Yes; Its possible.
    – Ramhound
    Commented Apr 8, 2016 at 13:27
  • 1
    It's possible, but unlikely... At least as simple as you think it is. A new motherboard will likely result in having to reinstall Windows. TBH, the safest thing is backup everything and reinstall OS and applications, then restore the data.
    – acejavelin
    Commented Apr 8, 2016 at 14:05
  • @acejavelin Why is that likely? Is there any way to find out in advance? Do you have some info / a link on the hard way to get this work if there actually is one? Are there any drawbacks to trying it or could it be that some things will break with the problems being hard to notice at first? If you're just concerned about the new mainboard and not the conversion etc wouldn't it be enough to install the drivers and maybe adjust some settings?
    – mYnDstrEAm
    Commented Apr 8, 2016 at 14:42
  • @mYnDstrEAm Depending on how different the motherboards are, the OS may not boot at all... Unless someone has done the exact swap with similar OS installation and drivers and posted it online you wouldn't know with reasonable certainty. Besides driver issues, you may no longer have a valid Windows license either.
    – acejavelin
    Commented Apr 8, 2016 at 14:46

1 Answer 1

Reset to default
1

Short version:

It's possible to do as you want, but it may not be the best approach in your situation.

Long version:

If you want to convert from a BIOS-mode to an EFI-mode boot of Windows, see this blog post. (There are other pages with similar information out there, too.) Note, however, that this page was written with the assumption that you just want to switch from BIOS-mode to EFI-mode booting without changing the hardware. You want to change the hardware, too, which introduces new complications. Windows really doesn't cope well with such changes, although intermediate to advanced Windows users are pretty skilled at making it work. Personally, I'd be more worried about that aspect of it -- but then again, I'm an expert on EFI-mode booting but not on Windows, so that may reflect my own skills and weaknesses more than anything else.

In any event, the process is basically two-fold:

  • Do the MBR-to-GPT conversion. This is fairly straightforward if you're lucky, but could get ugly if you use Windows LDM (aka "dynamic disks") or if your final partition ends without a gap of at least ~33 sectors unallocated at the end of the disk.
  • Install an EFI-mode boot loader. This task involves running a number of Windows tools to get the job done.

Both tasks involve some preparation and safety measures, like preparing backups and preparing boot media to use while the system is unbootable.

Instead of going through this hassle, you might want to consider backing up your personal data, doing a fresh install of Windows on your new computer, and then restoring your personal data afterward. This procedure is also a hassle, but it's less likely to go badly wrong, and it will save you from the hassles of getting Windows to cooperate with its new hardware, too.

Another alternative is to use the new computer's Compatibility Support Module (CSM) to boot in BIOS/CSM/legacy mode. You'll still have to deal with the hardware changes, but you won't need to cope with the partition table or boot loader changes.

Improve this answer
2
  • 1
    I suggest first migrating the Windows installation to the new hardware, get that working, then do the conversion from MBR to GPT only after that is working. There are numerous tools that will restore an image of HDD to new hardware, automatically doing what needs to be done, and allowing Windows to load.
    – Ramhound
    Commented Apr 8, 2016 at 16:57
  • Yeah, doing it in two stages as Ramhound suggests will at least make troubleshooting easier, since the problem space will be smaller if/when a problem occurs.
    – Rod Smith
    Commented Apr 8, 2016 at 18:18

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .