MacBook Pro (Mac OS X Mavericks) not displaying full resolution on external Philips QHD monitor I know this question has been answered a few times before in relation to other monitors and Mac OS X versions, but due to my limited knowledge I am after specific help with my setup.

I have a 2012 MacBookPro running Mac OS X Mavericks 10.9.5. I usually use a thunderbolt display with no problems, enjoying all resolutions on offer. I have just bought a Philips QuadHD 27" monitor (272B8QJEB/75), capable of 2560x1440, but am only getting max. 1920x1200. Yes, I have tried the option-click on the 'scale' drop down and I am using a 4K compatible cable. Is it possible to get the full resolution on this external display? I have seen fixes for other monitors and osx versions posted here.

Admittedly my knowledge is limited so a walkthrough would be greatly appreciated if there is a fix. I would prefer not to update to macOS Sierra as certain software I use will no longer work.
According to Apple, my MacBook Pro model will not support external monitors other than theirs. If I was to upgrade my MacBook I could use the screen I bought.