Mac Mini bad picture and font quality on Asus PB287Q 4K

If you do want 4K resolution on a Late 2012 Mac Mini, it is possible using an Active HDMI to Mini Display port connector. On Amazon it is:

Plugable Active DisplayPort to HDMI 2.0 Adapter (Supports displays up to 4K / UHD / 3840x2160@60Hz)

I have a 50" 4K flat screen hooked up to my Late 2012 Mini and with the above connector I am able to get 4K resolution. However I find it too small to use comfortably. The font and icons you can adjust but the menu bar remains painfully small. Plus for games the refresh rate is only 30Hz.

I would first try resetting the Mac Mini's NVRAM , as per > How to reset NVRAM on your Mac - Apple Support

If that does not help? Then I would try a different Mini DisplayPort to DisplayPort cable.

for example, > https://www.amazon.com/StarTech-com-Mini-DisplayPort-Adapter-Cable/dp/B002XVYZ82

Not all Mini DisplayPort to DisplayPort cables are created equal.

see > https://www.displayport.org/cables/how-to-choose-a-displayport-cable-and-not-get -a-bad-one/

Also FWIW, the Late 2012 Mac Mini's support 2560x1600 out of their Mini DisplayPort/Thunderbolt Port.

see > http://www.everymac.com/systems/apple/mac_mini/specs/mac-mini-core-i7-2.6-late-2 012-specs.html

I bought a new external screen. An Asus PB287Q. I hooked it up to my MacMini with HDMI. Then realised I can not get past a resolution of 1920x1080 and all the fonts look terrible.

That's because the 2012 Mac mini's graphics card can only support a resolution of up to 1920 x 1200 via HDMI. In order to get a resolution of up to 2560 x 1600 (this is still NOT 4K and would require a Late 2014 mini) you would need to connect the monitor to the mini's Thunderbolt port.

What you say is very true. The TV does have an upscale engine in it. The picture is beautiful, crisp and sharp. Alas, the menubar is the main drawback. I assume if the computer supported 4K than the menubar would be much larger. But then if the computer only supports 1920 X 1080 in HDMI why would it show the display in 4K resolution? Does it read the resolution of the display instead of its maximum resolution output? It also shows the higher resolution when Default for display is ticked. I would think regardless of what or how the display is connected or what display helpers are present only the max res would show. I am nowhere that versed in the handling of video signals so it's all Greek to me.

But then if the computer only supports 1920 X 1080 in HDMI why would it show the display in 4K resolution?

The computer is limited to what the GPU can provide. With this particular Mac mini, the GPU is limited to providing a maximum of 1920 x 1080 resolution on the HDMI port. I'm not familiar with the adapter that you listed, but it may have some "smarts" in it that can affect what the mini "sees" as what is connected to. Also, as you know, most smart HDTV can and do provide a level of upscaling. Regardless, upscaling is basically a "kludge" to make up for not having the proper initial video resolution to input for the maximum capability that the HDTV can work with. In this case 4K resolution. Only the very latest Mac can support this resolution natively ... and 8K is just over the horizon.

It's really no different than converting a lossy MP3 to a lossless audio file format using a "conversion" program. The end result is not truly a lossless file where the actual audio's fidelity is concerned.

You could also try SwitchResX.

... so basically 4K support, via this adaptor, is still not usable? ... and that it is NOT true 4K, but upscaled? Doesn't sound like Apple was wrong that the 2012 mini does NOT support 4K.