If I use 3d party software to convert disk from GPT to MBR, any backup of Windows 8.1 I save will probably not reinstall. As it’s installed on any UEFI / GPT machine, Windows 10 can automatically partition the disk. - Duration: 2:38:57.

Part 1. How to Install Windows 10 on GPT Partition. Any solutions to this problem?
I tried this twice using bare and never used SSD's and had the same result both times. Well, a few days ago Tony sent a PM telling what he wants to do: Dual boot Windows 10 Fall Creators Update and Fast Ring Windows Insider Fast Ring builds, doing this on small 120 GB SSD which is currently partitioned as an MBR disk but should be partitioned as GPT disk in new dual boot setup.
To Install Windows 10 on a UEFI Computer, Obtain the proper installation media. Installation disk writes that it cannot install on GPT disk. Confirm that Windows is installed to a GPT partition.

Instead of simply replying to him, I decided to … However, if I boot in UEFI mode, I can not even boot up the DVD. By default, Windows will generate a system reserved partition (on MBR disk) or recovery partition (on GPT disk) and C: drive if you select an unallocated space to install Windows operating system (OS). There are two ways of formatting GPT style partitions. I want to install technical preview on a 64x UEFI/GPT machine currently using Windows 8.1. Steps to Create GPT Partition in Windows 10. You can also install Windows onto a USB drive (Windows To Go), then move it to a GPT hard drive. The selected disk is of the GPT partition style." Take more control of Windows 10 Disk Partitions. Windows detects that the PC was booted into UEFI mode, and reformats the drive using the GPT drive format, and begins the installation. Since GPT disks can have multiple primary partitions as you like, it is no big deal to have one or more extra small partitions on a GPT disk, but things will be different for MBR disks, because you can have … Windows can not complete the installation process on the GPT partition, but it can completely run on the GPT partition once it is installed. On the Where do you want to install Windows? Boot into Windows; Open Disk Manager (For Windows 10, press the Windows key and the X key simultaneously, then click Disk Manager) You see three partitions including the EFI System Partition When Windows Setup starts, you will need to reformat your hard drive using the GPT partition table. The problem is that when I select the partition to install to, it says "Windows cannot be installed on this disk. In this post, we will be sharing with you the full instructions to perform both types of formatting. In the end Windows 10 was installed on a MBR partition rather than a GPT partition. Things could be easier if you are looking for ways to upgrade to Windows 10. He also has an additional 2 TB HDD for data. The drive will show a single area of unallocated space. Prerequisites. Googling around, I have read that you have to boot in UEFI mode in order to install Windows on a GPT disk.

Thanks.