When I go into the Precision X1 resize bar option, I see that the resize bar is not enabled. I verified this with the Nvidia control panel. The Precision X1 states that the “CMS support has to be disabled before flashing the bios”.  My current bios is 94.02.A0.00.5C, and my motherboard is a ROG crosshair VIII dark hero which supports resize bar.
When I go into the bios and disable CMS, and enable the resize bar, I get a blank screen on boot up, but Windows 10 does boot according to the event logs. After several power off reboots, I finally get a BIOS error on boot up stating that CMS was enabled and to press F1 to continue, or F2 to enter the BIOS. Note that the motherboard bios is the newest version as of this November.
When CMS is enabled on the motherboard, the resize bar is disabled.
Does anyone have solution to this issue.

I tried that and it works when I do a soft reboot, but when I turn off the computer and do a cold start, I get a blank screen. Windows is still working, but the video card is not out putting video.
 

Depending on your boot settings, turning CMS off might be causing boot problems. Your OS needs to be setup with GUID Partition Table (GPT) and UEFI BIOS mode. This article goes in to more detail on it in step 3. It's formatted for Asus products but the info is universal.

As others have said, you need windows on the right partition type ALTHOUGH I did have a problem with black screening the first time I turned on rebar and had to unplug the hdmi cable and plug back in for the display to work.   Weird stuff.

I have done MBR2GPT on three different computers of various ages with no problems.  The only issue I ran into was on the oldest (circa 2015) when it complained that the recovery partition was too small.  I set it aside and about a year later the recovery partition had magically doubled in size.  Don't know how that happened but I suspect some MS update did something behind the scenes.  Anyway, after that MBR2GPT worked fine on that computer.