Unsupported 4k monitors ??

[mrwuid]

Hi,
Hoping someone here may have faced similar issues and prevailed...
I have a Macbook Pro Retina 13 inch early 2013 which I am trying to connect to a cheap 4k monitor.
When I connect it only offers resolutions up to 1920x1080 (have tried the option key on display preferences etc). SwitchResX will scale it up - but the monitor is still only receiving 1920x1080.
The monitor works fine at 3840x2160 on my linux and windows desktops. My Macbook also happily drives a Dell 4K Monitor at work up to 3840x2160.
So why does my mac not like this monitor ? Is there a way to force it to a higher resolution ?
Thanks,
Michael

 

[Fishrrman]

What kind of a -connection/cable- are you using?

 

[mrwuid]

What kind of a -connection/cable- are you using?

I have been using a mini-display port to display port cable (plugged in to the thunderbolt ports. Same cable has worked fine on the work monitor - but not for the home one (or at least it works - but only at 1920x1080)...