I recently purchased a 21:9 LG monitor (model 29UM57) and I'm having difficulty getting my 2013 MBA to output to 2560x1080, which is the monitor's resolution. My max resolution is 1080p.

I purchased this MDP-HDMI adapter, Cable Matters® Gold Plated Mini DisplayPort (Thunderbolt™ Port Compatible) to HDMI Male to Female Adapter - 4K Resolution Ready, hoping that it would help my situation, but my max resolution has not changed.

I'm wondering whether ordering this HDMI cable, AmazonBasics High-Speed HDMI Cable - 6.5 Feet (2 Meters) Supports Ethernet, 3D, 4K and Audio Return, will fix my problem. I don't know what version or whatever my current HDMI cable is.

Please advise.

  • All the HDMI cables are the same! Did you try changing it from Display Pref's? I've a cheap Thunderbolt to HDMI cable and I was able to run 4K. Keep in mind your PC wasn't made to run that, so it'll take up a lot of resources. – user14492 Sep 15 '15 at 19:39
  • Yes, I have tried changing it from Displays in Preferences. Currently it is selected at "Default For Display", but it's maxing out at 1920x1080, which is still not the monitor's native resolution of 2560x1080. The other option, "Scaled", only gives me options of 1080p, 1080i, 720p, 1600x900 – none of which are of course 2560x1080. – N. Wong Sep 15 '15 at 20:22
  • I have also ordered the same mdp-hdmi adapter after reading that comment on reddit. Were you able to solve it somehow? Please let me know. Thanks in advance! I was able to solve temporarily using switchresX on MBA after turning off SIP (which I don't feel good about). – woooh77 Jul 5 '16 at 21:26

I believe the problem is your HDMI cable - it's not capable of displaying a resolution of 2560x1080. In other words, it's pre-HDMI 1.4 specification. (Also, the link provided to the cable in the original question is out of date; it's no longer available).

Per Apple Support, the 2013 MacBook Air (11" and 13" model) has a Thunderbolt port which also supports mini Display Port.

enter image description here

Since the HDMI cable referenced in the original question is 4K capable (HDMI v1.4 specification), the cable is not the issue. What wasn't mentioned was the HDMI adapter. I believe this component to be the "weak link" in this chain because if the mDP to HDMI adapter isn't 4K capable, nothing else will matter.

I recommend getting an active mDP to HDMI adapter (rather than passive) and then connecting your HDMI (v1.4 or above) cable from the adapter to the TV.

enter image description here

That said, I would only recommend this solution for this particular setup, because the LG monitor 29UM57-P only supports HDMI connections.

Ideally, you would want to use mDP to either mDP or DP connections rather than convert to HDMI, DVI, etc., to get the most reliable connection(s). Less conversions means less points of potential failure.

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According to the technical specifications page for the MacBook Air (13-inch, Mid 2013) you should be able to output at 2560x1080.

You might want to consider using one of the two mDP-HDMI adapters that Apple sells on their online store: in the US, at least, those are the Belkin 4K and Moshi.

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Per top rated answer, try this active adapter

comment on Amazon

If you have a Macbook Air from 2013 (possibly other models) and want to use an LG UltraWide monitor that is 2560x1080 @60hz, then this cable WILL NOT work for you. However, the following cable - "Cable Matters Active Mini DisplayPort to HDMI Adapter (Active Mini DP to HDMI) Supporting Eyefinity Technology & 4K Resolution" - https://www.amazon.com/gp/product/B00PJ3LSIG/ref=od_aui_detailpages00?ie=UTF8&psc=1 - works perfectly for the job. Hopefully this will save somebody some time!

I'm sure this particular cable is fine for the right job - I just had to rate it something, even though it wasn't right for my case.

I ordered the active adapter and it worked for my LG Ultrawide: go to display settings on macbook air first, select best for LG Ultrawide then plug in cable with active adapter, then in display settings select the 2560x1080 resolution.

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