Can't get 2K resolution on 4K monitor

[bazmattaz]

Hi folks,

I'm pulling my hair out with this one and I'm wondering if anyone can help.

I have a MacBook Pro (Retina, 13-inch, Late 2013) and a 4K monitor ACER CB280HK.

I want to get 2K resolution (2048×1080) on my monitor but the options I have in display are only these:

I have tried to use SwitchResX to get 2048×1080 but it's really choppy.

I dont understand the specs say I can use;

Dual display and video mirroring: Simultaneously supports full native resolution on the built-in display and up to 2560 by 1600 pixels on up to two external displays, both at millions of colors
​

I'm connected via thunderbolt (Mini display port)

Does anyone have any ideas why this might not work? My windows machine displays 2K just fine on this monitor!

Thanks all!

​

 

[Fishrrman]

The image that was supposed to show us the resolutions that are available to you doesn't show up.
How about listing them "as text".

Try the following:
a. open the displays pref pane
b. select the external display
c. HOLD DOWN THE OPTION KEY and click the "scaled" button.

What resolutions are available to you?

If you can't get the particular one you want in the Displays pref pane,
and
If you can't get it using SwitchRes, either...
then
You probably aren't going to "get it"... (sigh)