Dell UP2715K support is busted

Originator:josh.deprez
Number:rdar://22947671 Date Originated:10/1/2015
Status:Open Resolved:No
Product:OS X Product Version:15A284
Classification: Reproducible:Always
 
Summary:
Upgrading to El Cap resulted in weird 2560x2880 resolution on 16:9 Dell UP2715K 5K monitor

Steps to Reproduce:
1. Upgrade to 10.11
2. Plug in Dell UP2715K with 2x DisplayPort cables

Expected Results:
Full 5120x2880 "retina" resolution, just how it used to work on 10.10.

Actual Results:
Weird 2560x2880 resolution, with 1x2 pixel size, and only the right half of the screen is visible. Have to unplug and plug in only 1 DisplayPort cable to get 2560x1440 (or other reasonable configuration). 

Version:
15A284

Notes:


Configuration:


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