2560x1440 or 2560x 1600 resolution with mac Mini 2012 on HP 4K monitor?

[jmscal]

Hi

Recently purchased an HP z27 4K monitor. I have a 2012 mac Mini which supports up to 2560 resolution - I had a Thunderbold 27" display and it worked fine.

I got a Mini DisplayPort to Mini DisplayPort cable which provides input to the monitor but what is strange is 2560 resolution is not an option?
When I hook up the Mac mini I get a maximum resolution of 1920 when technically I should be able to get at least 2560 - when using alt/option let it is not even offered as a choice.

Additionally when I hook up my MacBook Air mid 2013 I get the same maximum resolution whereas this computer should also support resolution of the 2560

My partner has a 2018 Macbook Air that with USBC achieves 3840

What is also strange I can select 3840 on the mac mini and it seems to work- but the scale is way too small

So my questions are
1. How can I get 2560 using both these computers o. This monitor ( the specs of the cable, monitor and computer all support this) - should I perhaps try a Minidisplay to DisplayPort cable ? or is it something else?
Thanks

 

[joevt]

Open Displays preferences panel, hold the option key down and click "Scaled". Click "Show low resolution modes". Is there a 2560x1440 option now?

Try SwitchResX.

Post some screen shots of the Displays preferences panel and SwitchResX resolutions.

If the problem is not solved, then checkout #4 for other information gathering ideas so we can see what the problem is.

 

[DeltaMac]

It's possible that your cable does not support the resolution that you want.
Try a different (brand) cable. mDP to mDP should be OK, but try mini DisplayPort to DisplayPort.