Windows 10: HDD not listed in UEFI mode even after GPT conversion.

Hello everybody,

i need help with something.I was using the legacy bios mode (MBR) for a long time now but i wanted to switch to UEFI mode so i used mbr2gbt.exe to convert my hdd to GPT after the conversion was complete it said on the black screen that i had to change my boot mode to UEFI in order to boot into windows 10 so i restarded my computer and entered the bios and i changed my boot mode from LEGACY+UEFI to UEFI then i saved everything and rebooted my pc but for some reason it doesn't boot to windows it boots to EFI Shell and both my Hard Disk and my DVD-RW are missing from the boot priority list.Please i need assistance with this situation

Thank You *Smile

By the way I'm from Turkey so sorry for bad english *Smile

:)

 

uefi installation drivers for windows 10 64 bit on asus motherboard h 170m plus with uefi ami bios since i have single 3 tb seagate internal hdd

i built a new pc with asus motherboard asus h 170m plus with uefi bios n intel i 5 6400 processor n seagate single 3 tb internal hdd . when i tried installing win 10 home from microsoft supplied usb it installed in mbr format n only 2 tb was usable rest
800 gb was marked as unallocated space . so i tried to install win 10 after converting hdd in gpt format with cmd . though the usb is detected as kdi msftwin10 pmap in uefi mode after setup starts it says windows cant be installed in this disc as it is gpt
. now how to install win 10 in my new pc in uefi gpt mode so i can use all 3 tb

 

Getting error: Windows cannot be installed to this disk. The selected disk is of the GPT partition style

Hi,

You might have better luck with the Boot Options that you get with the F12 key, or whatever your machine uses...

You want to look for something like UEFI USB Flash Drive, or maybe even UEFI USB HDD...

You might even find your Flash Drive itself listed there under UEFI...

The reason you are getting that error is that the flash drive did not boot in UEFI Mode...

You might also want to try making a new one with RUFUS... I have used this before and had it change my settings when I changed another... For instance... If I set it for GPT and then set it to Fat32, the GPT would change back to MBR... Of if I set Fate 32
first, when I set it to GPT, the FAT32 would change to something else...

It sometimes would take going through the settings several times to get them to stay at what I wanted...

 

Hi, the Windows partition layout for an EFI booting system is quite different to that for one using legacy BIOS.

The first has 4 partitions, the second, 3.
BIOS/MBR-based hard drive partitions | Microsoft Docs
UEFI/GPT-based hard drive partitions | Microsoft Docs

A legacy BIOS cannot boot an OS on a GPT disk.

Thus your disk is unbootable as you've found.

Now I could tell you how to take a valid Windows partition from one GPT disk to another and create a bootable system.
What I don't know whether that would work with a Windows partition created under legacy BIOS.

I'll be interested to see what others suggest as I don't want to play guessing games.

How big is your disk?
Do you have a backup or disk image of your original BIOS disk?

 

1.Size of the hdd is 1TB
2.I don't have backup of bios

 

Try changing it back to Legacy+UEFI. If that fails,
I would start fresh reinitialize the drive GPT and Install Windows with the GPT+UEFI option. Loosing all data.

Change the Bios to Legacy,
Boot off of Windows install Media, choose your Language and press Shift+F10 to go directly to the Command Prompt.
Here type Diskpart and press enter. At this prompt type the following Bold commands and press enter after each one
ii) list disk
(ie) DISKPART > list disk
It now lists disk by number
you have to select the disk next with
iii) select disk <disk number>
(ie) DISKPART> Select Disk (disk number) = as listed in previous command. The selected disk now has an Asterisk next to it.
iv) clean (this erases all data on the Disk, so be sure you choose the correct one)
(ie) DISKPART> clean
v) convert gpt
vi) create partition primary
vii) format fs=ntfs quick
now for verification of disk status and free space type
v) list disk
the status should be "online" and free space should be "disk size"
‘vi)exit
Remove install media, Shut down computer
On another computer, if you have a Windows ISO image, create a bootable GPT/UEFI USB Windows installer with Rufus. Be sure to change Partition Scheme to GPT for UEFI.
Put the USB Flash drive in the troubled computer, boot into Setup (Bios) change Boot mode to UEFI Restart the computer and go back to the Bios Boot Tab, the Flash Drive should now be listed as bootable media, move this to First Boot Device, Save and Exit.

 

Thank you so much <3 it worked Thank you all for all the assistance