Problem using External Monitor with MacBook Pro

I have a MBP "Core i7" 2.6 15" Mid-2012 ( MacBookPro9,1 - A1286 ) and want to use a larger screen with it. I checked on EveryMac, and the maximum display resolution for a second monitor is listed as 2560x1600. So I bought a 30-inch monitor with that native resolution - a Dell UP3017 - and hooked it up (via a DisplayPort to HDMI cable).

However when I now check About This Mac > Displays, while it correctly identifies the monitor as a Dell UP3017, it lists its native resolution as 2048 x 1080 ( a resolution which is see is known as "Full Container") and System Preferences only offers resolution choices at this 1.9:1 aspect ratio, so that everything displays as vertically elongated. This is despite the fact that both the MBP and the monitor have 16:10 native aspect ratios.

Have tried restarting the MBP, but I'm getting the same issue.

Not sure whether the problem might be my cable, so I'm trying to figure out what kind of cable I should be getting to persuade the monitor to display at its native aspect ratio. Any help much appreciated...

MacBook Pro 15″, macOS 10.12

Posted on Mar 27, 2024 10:14 PM

Top-ranking reply

gordon k Author

Level 1

49 points

Posted on Apr 2, 2024 4:44 AM

OK, in case anyone has a similar problem and finds this thread...

The issue is, on a number of monitors (including the UP3017) the HDMI implementation tops out at 1080 vertical.

MacBook sees this & goes for the max resolution it can kick out within that limit - Full Container - 2048 x 1080.

Solution : the monitor's DisplayPort input, plus a £6 Mini DisplayPort to DisplayPort Male Cable from eBay.

Now have the full 2560 x 1600, no stretching. 👍

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Problem using External Monitor with MacBook Pro

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