Q: How to display 2560x1080 on external monitor from MBP or MBA?

r23w, Sorry to insist, but after test of different cables (Mini DP > DP // Adaptator Mini DP > HDMI + HDMI > HDMI), the problem persists. I have the same compression on the left of my sreen when I'm in 2560x1080.    The "best" solution for the moment is 2048x864....

I don't know what to do...

Same here. 

Seems to be something within OS X.  I'm running 10.9.3.  I installed Windows 7 via Bootcamp and it looks perfect.  I reeboot to OSX and same problem as before.

Thanks for the hint with the DP-Cable. I had the same issue with my MacBook Pro Retina (mid 2014) and the LG 25UM55-P. Switchresx worked pretty well with the mentioned settings but only with 53Hz. I ordered a Lenovo DP -> mDP Cable (http://www.amazon.de/gp/product/B008XTW666?psc=1&redirect=true&ref_=oh_aui_detai lpage_o02_s00) and now it works perfectly out of the box with rotation, 60Hz and the native resolution.

Thanks!

Thank you for you screenshot, it is working! I tried several parameters, but it always shows inactive after reboot. But your parameters work pretty well. Thank you again for sharing.

This worked for me though only with the MacBook Closed.  It is a Mid 2010 MacBook Pro 13.

Changed the Scan Rate until I hit the pixel clock of 159.84 as suggested in an earlier post.

I am using a Cable Matters Gold Mini Display Port to HDMI Adapter (Female) with a cable into the monitor.

Also works with an IO Gear HDMI KVM Switch

MacBook Pro 13 Mid 2010

8GB Ram

256GB SSD

You exact settings worked flawlessly with my LG 25UM56-P using Switch Res X 4.4.1.

Thanks for posting your screen shot!

Cheers!

Hello, i have LG25UM47 display and Macbook Air 13 2104. Display is connected via mini display port to HDMI (it support resolution to 4K , it was bought in original store) and HDMI cable. But the resolution is still 1980x1080 , i tried to use switchresx but it do not work . Do you have any idea how to solve this problem ? Thank you for your reply.

Had the same issue here: https://discussions.apple.com/message/29157819?ac_cid=sa123456#29157819

Have copied and pasted my fix below:

Ok I fixed it. I don't know why this is working but at this stage I dont care.

This is exactly what happened:

I read somewhere deep in the bowels of like the third or fourth page of Google that a guy got it working by closing his macbook at the same time as using DisplayPort Wire ("DP")--> Mini DisplayPort ("Mini DP Adapter"

I was using a HDMI cable through the Mini DP Adapter. I thought, ok let me try plugging in the DisplayPort wire at the same time (the adapter has a port for both which can be used simultaneously) then closing the Macbook.

So I plugged in the DisplayPort wire, and nothing happened as I have to change the input to DisplayPort on the Monitor from HDMI. I changed the input to DisplayPort, and it said NO SIGNAL (which was my issue)

Then I closed my bleeping Macbook, and VOILA THE SCREEN BURSTS INTO LIFE FULL 2560x1080 !! So I was happy but also slightly upset that I couldn't use my new monitor with my MacBook open, but hey whatever.

Well, what if I can? So, I try opening the MacBook, AND THEY BOTH WORK PERFECTLY.

PLOT TWIST: All the while, the HDMI cable is still plugged into the Mini DP Adapter and into the Monitor. So I thought, well closing the Macbook must have refreshed something or something else or blah blah, so I can remove the HDMI cable.

I remove the HDMI cable from the Mini DP Adapter AND THE MONITOR DISPLAYS NO SIGNAL!! WHAT IS LIFE!?

SO MY MONITOR IS WORKING WITH A HDMI CABLE AND A DISPLAY PORT CABLE BOTH PLUGGED IN THROUGH A BLEEPING MINI DP ADAPTER WITH THE INPUT SET TO DISPLAYPORT.

Being a man of (reasonable in my own completely unqualified and probably wrong opinion) logic the ONLY THING I CAN THINK OF IS THAT THE MINI DP ADAPTER  DRAWS POWER FROM THE MONITOR!? AND THE DISPLAY PORT CABLE WASNT PROPERLY POWERING IT!?

I don't know. At this point, I don't care. Well I do, its still bugging me, but it works. I can't tell you why.

SwitchResX does not work anymore with the latest version of Max OSX (El Capitan).

Or at least there is no easy answer for simple users as me.

But the DisplayPort cable solved the problem instantly. No trouble whatsoever.

I have the same issue and have read your fix but Im confused with what cables/ports/adapters you used to fix the issue.  Could you post a link to the products you used?

I use a Display Port to mini Displayport cable like this:

http://www.amazon.com/Cable-Matters®-DisplayPort-Thunderbolt-Compatible/dp/B00C7 RJQPY/ref=sr_1_1?ie=UTF8&qid=1446746715&sr=8-1

And then you use a display port to hdmi cable to connect to the monitor?

No, I use a LG 25UB55-B.AEU which has a direct DisplayPort input.

Hey man,

For me the displayport - minidisplay port cable on its own didnt work.

What did work, bizarelly, was plugging both the hdmi cable and the displayport-displayport (normal not mini) into the Monitor, and connecting the other ends to this exact product:

https://www.hama.com/00053245/hama-3in1-mini-displayport-adapter-for-dvi-display port-or-hdmi-

Then I plugged this adapter into my MBP, naturally. For me if I didnt have the hdmi cable in, the macbook didnt recognize the monitor existed. Im not sure why, possibly because the adapter is faulty, but hey this is what worked for me. So i have two cables connecting my monitor but whatever. I'll take it. Working flawlessly.

Hope it helps.

Cheers.

I have this monitor: http://www.lg.com/us/monitors/lg-29UM57-P-ultrawide-led-monitor

Which only has 2 HDMI inputs.  I have tried using a mini DP to HDMI with no luck.