LG ultra wide screen

I can also activate it, but it is out of range when I apply this custom resolution. I guess it is because the vertical scan rate should be 60.000 Hz.

When you add a custom resolution, the app automatically gets the parameters in use (as far as I could understand). I just changed the horizontal resolution from the following screen and, after hit OK, the program automatically changed the frequencies.

1 - If the computer is configured for 1080P60, when you add a custom resolution, you should see something like this:

2 - After hit OK, save the configurations you just made. Then, watching its details, you should have something like this:

You can also try creating the custom resolution using the Copy and Paste feature. Copy from the Current Resolutions (one that works well) and Paste in the new Custom Resolution, changing only the horizontal resolution to 2560.

I don't know much more about the SwitchResX. I'm hoping the Apple update will come before the 10 days trial. Remember to save and Reboot the computer. After rebooting, you can see if the resolution was accepted or not.

I hope it helped.

Thank you for your help. I have exactly the same configuration than you, but in my case it is not working the status is active but out of resolution on the display. 😟

This has been an issue since day one of the Beta... Come on Apple!

I've been wrestling with this (enabling ultrawide resolutions) under El Cap, and now Sierra. I'll be pleasantly surprised if Apple actually fixes this in Sierra, but in the meantime...

The do-it-yourself solution does involve (temporarily...under most circumstances) disabling SIP, which unfortunately for me involves multiple extra steps of pulling and swapping the graphics card from my Mac Pro, doing the work, then putting everything back again afterwards, since SIP can only be disable/enabled from the Recovery Partition, and if base OS X does not support a video card out of the box and requires a driver (like the Nvidia 9xx-series), you can't boot into the recovery partition.

Anyhow, the steps are as follow:

1. Turn off SIP (there are step-by-step instructions out there for this, it's quick and easy)

2. Create custom resolution in SwitchResX for monitor, save resolution (for me, 2560x1080, 52.52Hz)

3. Turn on SIP

Simple, right? Well, sort of. There are numerous potential variables, which you'll see when you dig into this -- HDMI vs DisplayPort, single vs dual-link DVI, pixel clock, even the brand of HDMI cable, etc). This solution should work for pretty much everything though. One important piece of information is that Apple has limited the pixel clock value (and this is not done in Windows, Win 10 booting on the same Mac Pro works perfectly without any issues for me). That means that with a 2560x1080 (or other very high resolution) display, you can't get it to 60 Hz, even using SwitchResX -- thus the 52.52Hz vertical refresh value I used above.

If you really want to force a higher pixel clock value, to enable higher resolutions at standard display rates, there's a pixel clock patch process, which you can find here: https://github.com/Floris497/mac-pixel-clock-patch-V2

It works, and once you've done it, you can set higher pixel clock maximum (and therefore higher refresh rate) with SwitchResX -- the problem is that under some circumstances (like using an Nvidia card in a Mac Pro...) to use it you may have to leave SIP disabled, which is really not a good idea. Personally, I'd rather put up with the 52 Hz refresh rate, but your mileage may vary.

Hope this helps.

Thank you for your explanations Chelidon, they are very clarifying. I've trying to increase the refresh rate to 60 Hz, without success just as you said.

And, by the way, my LG ultrawide monitor was working perfectly with El Captain OS.

Problem solve.

Thank you for the info. It worked perfectly for me.

MacBookPro Retina, Sierra with LG Widescreen 29"

I am extremely puzzled by at the methods and work-a-round for this Ultra-Wide screen issue.

My MBP worked 110% with a LG-25UM57 ultrawide screen on El Captian.

Now in Sierra ... broken, stretched and useless!

Oh BTW, Sierra work 110% on my Mac Mini as it did with El Captain. (2560x1080)

So why, oh why must I load 3rd party apps, create profiles and tweak everything ...

WHEN IT SHOULD BE WORKING NATIVELY!

Come on Apple is it that hard to fix?

I'm really, really disappointed. Is Apple forcing us to buy "Apple-olnly" screens... (That not exist anymore)

Having the same issue, very annoying, plus there are a number of other bugs. I do regret updating it to Sierra.

Same issue for me on LG ultrawide.

I am running the 10.12.1 beta 2

I refuse to install 3rd party apps to make Sierra work. Seems like they hired too many Windows engineers.

I have this problem too! Apple can you fix this with an update? My MacBook Pro Retina 2013 worked great with a thunderbolt>HDMI adapter before the upgrade to sierra now my computer will not 2560 width anymore. Please help. This is my primary monitor and it is very annoying. Thanks

I found a fix...

If I have the laptop opened when connected to the ultrawide display it fills the full ultrawide display, if I close the laptop it does not...

Dead simple, but it works lol