Fresh clean install of Windows 10 64 on 790 is straightforward. No Dell driver download needed. Done it 6-8 times on this model MT. Works perfectly. The free Microsoft Windows 10 download media is by default 64 bit when I did it. Only catch might be activation. I always did Win 10 Pro 64. Maybe your new install activation will be automatic on line.
Even 4 gb is good enough for student work.