Mac Pro not recognizing correct monitor?

Hello,

I have a 2009 quad core Mac Pro with the basic setup running the latest El Capitan. I decided to splurge on an LG 25UM57 ultra wide monitor. The LG monitor has only two HDMI ports, no DVI or VGA. I am using a mini display port to HDMI adaptor with an HDMI cord to connect the monitor. The problem is, I can't get the Mac Pro to recognize that I'm using an actual monitor, not a television.

I'm assuming that I need to purchase a DVI to HDMI adaptor to get the correct screen aspect ratio and setting? It is supposed to be 2560x1080. I've tried holding the Option button when I clicked on the Scaled button in the Displays preference pane, but I didn't get the option for the full 2560x1080. Is there anything else I might've overlooked?

Thanks!

Jerry

Mac Pro, OS X El Capitan (10.11), 2009 2.66Ghz quad core

Posted on Oct 8, 2015 5:29 PM

23 replies

Dec 6, 2015 10:28 AM in response to jerry7171

jerry7171--

Did you install the LG software to get this split-screen behavior?

The documentation is vague about whether the display itself (without the split screen software) would support 2560 by 1080p directly.

The Mac (without that software) depends on the resolution reported by a query directly to the display (not to the software that may be intervening).

I think it accurately reports the display itself can do 2560 by 1080, but your problems May be caused by the split-screen software.

jerry7171 Author

Level 1

21 points

Dec 6, 2015 1:27 PM in response to Grant Bennet-Alder

I didn't install the split screen software. I figured Mission Control would be more than adequate for my needs.

One of the things I did prior to purchasing the LG was double check the maximum output for the GT 120 graphics card. According to everymac.com it should have worked. In hindsight, I wonder now if I had used both ports on the GT 120 with adapters to plug in both HDMI ports on the monitor if it would have worked after all? I still have my GT 120 card, but I've stored it away just in case I need the boot screen in the future. I might have to try using it at that time just to find out.

One other thing I recall is that when I was attempting to get my Mac Pro to recognize the LG and the proper screen resolution, my Mac Pro wouldn't go above 1080x1920. I was also only using one of the HDMI ports on the rear of the monitor. It is the best explanation I can come up with as to why I had so much frustration.

Even with the EVGA graphics card that can push 4K resolution easily, I still couldn't get the full 2560x1080 until I plugged in both HDMI. It is quirky for sure, but at this point, I'm just happy to finally have the monitor being used to its full potential (finally).

I really like this monitor, but LG really needs to step up the manual for it. Overall, the manual is only barely usable. The trouble shooting section never mentioned the possible need to use both HDMI ports to get the full resolution if it wasn't working correctly. I'm just stupid lucky that I tried plugging in both HDMI ports on a whim.

Dec 6, 2015 6:56 PM in response to jerry7171

I really like this monitor, but LG really needs to step up the manual for it.

Amen to that!

The only tiny suggestion about the way this is intended to behave is an obtuse reference to the display as "Dual Controller", and no additional practical information about how to deal with that.

Dec 20, 2015 10:35 AM in response to Grant Bennet-Alder

I guess Im lost as to why plugging your TVs HDMI into the 2nd HDMI port fixed it all. Im assuming your TVs HDMI cable is a TV out? did you have to select HDMI 1 of HMDI 2 on the monitor?

Maucir

Level 1

5 points

Jan 8, 2016 8:06 PM in response to jerry7171

Do you actually mean connecting just the cable (without the TV on the other end)?

Jan 9, 2016 7:25 AM in response to Brent-Shocky111

This particular display behaves like certain 5K displays. It requires TWO computer ports to drive it.

Maucir

Level 1

5 points

Jan 9, 2016 4:21 PM in response to Grant Bennet-Alder

Sounds like the problem is that the MacBook Air doesn't support the above resolution... I'm screwed...

chelidon

Level 1

28 points

May 24, 2016 8:05 AM in response to Maucir

Try SwitchResX -- it's worked for others with this display and MBA.

http://www.madrau.com

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Mac Pro not recognizing correct monitor?