The upgrade process takes about 4 hours on the MS-1 chassis.
The upgrade took about 1 hour on my old CAPS server using the Atom D525 (1.8GHz) processor but there are some tricks involved:
Make sure Windows 7 has all the Windows Updates installed (without errors). I left the server on for a week and let Win 7 automatically download updates because manually updating was a failure.
Download and run the Windows 10 Media Creation Tool - use it to install or reinstall Windows 10 using a USB or DVD. https://www.microsoft.com/en-us/software-download/windows10/
Type CMD into the Start search window to get a command prompt, in the new window type "cleanmgr" without the quotes. Clean your "C" drive.
Use the free CC cleaner to clean the registry only, the other parts clean way too aggressive for me, I want my cookies and other stuff. https://www.piriform.com/
Download the free Paragon Backup and Recovery and image your C drive to a separate backup drive, don't forget to make a boot disk. https://www.paragon-software.com/home/br-free/
Do a reboot
Put in the Windows 10 disk you made and upgrade
Uncheck everything in the 3 setup pages when asked, you can enable them later if you want
Turn off all the Windows 10 phone home programs - http://bgr.com/2015/07/31/windows-10-upgrade-download-install-tips-tricks/
Once you have Windows 10 installed and registered you can roll back to Win 7 or use the disk or USB you made to do a clean install of Windows 10.
Since your computer was registered with Windows 10, you can now format the C drive, install Windows 10 from scratch and it will be re-registered. For now, this is the only
way to do a clean install with the free upgrade.