Well I'd forgotten how atrocious the KDE partition manager was.

Well I'd forgotten how atrocious the KDE partition manager was. I downloaded and burned a new live version of GPartEd, which has always been the most reliable and capable of the open-source partition editors.

The KDE partition editor couldn't see the free space on the disk, whereas GPartEd could. I'm adding space for some things (especially the Windows system partition) and adding a logical partition at the end, where I'll relocate stuff like the Extras drive and the Music collection.

But, it take s-o-o-o-o-o-o-o-o-o-o-o to move and resize partitions - I'll get back to it later. Once it's all done I need to reboot both Windows (which will automatically do a CHKDISK) and Mint. I might reinstall Mint anyway, after backing up the /Home partition. I don't use Mint much, but it does come in handy every so often, and some software runs better on it.

Ultimately I want the Studio PC to be the one I do 3D building and Videos on, so more space is essential.
https://gparted.org/livecd.php