Almost any decent computer can probably run a mill if it has the proper specs. If you plan on using it daily, and you care about being efficient, there is a downtime when the computer is processing, maybe its <1 min per case, or 2 min per puck, this time adds up in the long run, not to mention, while youre waiting, that 1 min becomes 15 minutes as you wander off into DLN land and forget to start the mill..
Software is changing really fast, and DHC doesnt just sell super-fast liquid-cooled computers, its a dental specific computer, with your software loaded onto it for you, tech support, antivirus that will help protect sensitive HIPAA info on your computer, their own file sharing inbox for IOS scans and sending to multiple mills etc. I have a dell optiplex i5 that has run a scanner and mill for 5+ years now, works fine. I also bought a dell laptop from walmart that was dead JUST after the warranty was up, go figure. I wouldnt put it past a company like dell to have a kill switch feature that waits until you need parts and service from them, just sayin.. I also have an alienware i7 touchscreen and it runs 3shape/exo just fine, you can cast it to a tv or run hdmi. Its just depends on what you want, and how much $$$ you wanna throw down, not all are created equal, and why not go with a dental specific company that has your best interest in mind, its just as important as the scanner.