We are looking to buy a computer for live presentations in one location, I was hoping for and updated IMac but that didn't happen. So now I'm torn between the dated IMac or the New Mac mini, which would you buy?
[doublepost=1541026030][/doublepost]What about graphics and over all speed, the 27 inch monitor will be plenty big enough for the user. We will output to to 80 inch screens
The Mini will do well, the price is right and the portability (if important) may be more manageable. For displaying static or even video content it should be no problem. The monitor size is not really the Mini's concern, it sends the signal to the monitor and the monitor renders it.
That said, larger screens with 1080p content will be grainy up close, but ok from a distance. The HDMI port can drive 4K monitors. The Thunderbolt ports can drive 5k resolution. Here is a site that suggests optimal distances for viewing content at various resolutions and screen sizes. Not sure how accurate, but it should give you a fair idea.