Can't Install Windows 10 to a GPT Partition

I'm pulling my hair out here.

PROBLEM:
Can't install Windows 10 x64 from an OEM disk ... to a Samsung 850 EVO 500Gb SSD ... on a GPT partition. It installs instead on a MBR partition.

SPECS:
Motherboard: Gigabyte GA-Z170X-Gaming 7
Bios version: F4
SSD: Samsung 850 EVO 500Gb ... bare and never used ... this is Drive 0 (aka Drive C)
Media: Windows 10 x64 OEM disk
i7-6700K

WHAT I DID:
In the bios I set "Windows 8/10 Features" to "Windows 8/10" and set "CSM Support" to "Enabled" (default). I inserted the windows 10 disk into the DVD drive. I booted and hit F12 to set the boot priority to the DVD drive ... F12 detected the SSD and 2 instances of the DVD drive ... one contained the UEFI string and the other didn't. (Note that if "CSM Support" is set to "Disabled" ... NO drives are detected.) I booted using the DVD drive with the UEFI string. Windows started to load but did not give me an option of HOW to format the SSD ... it only gave me the option TO format the SSD and no other information. In the end Windows 10 was installed on a MBR partition rather than a GPT partition. I tried this twice using bare and never used SSD's and had the same result both times. As I understand it ... if I boot to the DVD drive that contains the UEFI string and the Windows 10 disk ... Windows 10 should be installed on a GPT partition. Evidently I'm missing something.

QUESTIONS:
1. What am I missing ... how do I install Windows 10 on a SSD and a GPT partition?
2. Any particular bios settings to be aware of ... or something else such as software or drivers?
3. How do I delete all partitions on the SSD so I can start over?

When you reply assume I'm an idiot ... I'm really not ... but specificity is always helpful.

Thanks!

KenB

I selected the UEFI DVD drive for the installation. On the bare drive the installer created the partitions it wanted ... and installed using MBR. The only options I was given were New, Format and Next ... I was given no option as to HOW to format (MBR or GPT) ... only the option TO format was given.

Right now I'm totally lost.

How do I delete the partitions on my MBR formatted SSD so I can start over?

Thanks!

KenB

When you see the Windows setup screen, press shift + F10 to open a command prompt. Then enter:

Diskpart
List Disk
Select Disk # (# will be the disk number of the SSD shown from list disk. It is probably 0. Be sure to select the correct disk!)
Clean
Convert GPT
Exit
Exit

@NavyLCDR

OK ... that got me back to an empty SSD with GPT. But now what?

With CSM Support disabled ... the SSD isn't detected. I just can't figure how to get out of this Legacy Mode trap and have the SSD detected as UEFI.

Thanks!

KenB

This is what I would do. Disable the Windows 8/10 features in BIOS. Disable secure boot in BIOS. Make a USB Flash Drive of Kyhi's recovery drive:
Windows 10 Recovery Tools - Bootable Rescue Disk - Windows 10 Forums

To make the USB flash drive of his recovery drive all you do is format a USB flash drive to FAT32 (it doesn't need to be a big one, 2 GB is fine. Get an 8 GB one if you also want to make a Windows 10 installation USB while you are at it, see the note on the link to his recovery drive). Mount the ISO file of his drive and copy all the files from the mounted ISO to the USB flash drive. Boot the computer from the UEFI listing for the flash drive. See if the SSD shows up in either diskpart or MiniTool Partition Wizard. Do not partition the SSD.

If the SSD shows up, it should be all unallocated space. While still in Kyhi's recovery drive, insert the Windows 10 DVD. From either command prompt or file explorer from Kyhi's recovery drive, run setup.exe on the Windows 10 DVD and try to install Windows 10 that way. Watch for the first reboot in the Windows 10 setup and in the countdown for rebooting, pull the USB flash drive out and eject the DVD. If you don't get to it before the computer reboots, it might reboot into either Kyhi's drive or Windows setup again. Just pull out the USB flash drive and DVD at that time, power off the computer, and reboot it without them in.

I got the same error, something along the line of could not install windows because partition is GPT. And the windows installation partition manager was useless. So I duckduckGoed binged and found this thread.
Here is how I solved the problem:
Thanks to the tip above, and the IT guys at work also mentioned the diskpart application.
Run the windows install. Mine is on USB.
Instead of installing, click on Troubleshoot. And find your way to the command prompt.
Type:
> diskpart
> select disk 1
> clean (might be redundant)
> convert mbr
> exit
Then reboot and install windows.

Good luck. And may the odds forever be in your favor, force be with you.