Srkee

then it comes to the software using CPU or GPU or both for rendering. I dont know your software yet (what is it?) but it's more common to be CPU-based, only really complex CAD work use GPU power well.
 
Also what i3 and i5? They have more cores since 8th gen so I need to ask that.
 

software that lets multiple people use one computer at a time with their own keyboard, mouse and monitor.
 
Look here for the microsoft version https://docs.microsoft.com/en-us/windows-server/remote/multipoint-services/introducing-multipoint-services
 
 

for one user?

Have you looked at multipoint before? THere is one that is included in windows server and should work well here, and allows you to do this without making vms.

honestly if currently an i3 and gtx1050 do the job kind of okay you are better of just upgrading that computers, this will be cheaper than buying a server, requires less setup time and if something fails only one computer is not working instead of all of them.