Google and you'll find a bunch, but sure, here's one: http://arstechnica.com/apple/2014/03/first-os-x-10-9-3-beta-comes-with-improved-4k-display-support/ http:

Google and you'll find a bunch, but sure, here's one: http://arstechnica.com/apple/2014/03/first-os-x-10-9-3-beta-comes-with-improved-4k-display-support/ http://arstechnica.com/apple/2014/03/first-os-x-10-9-3-beta-... 60 Hz 4K appears to require DisplayPort 1.2, which I believe is currently only available on the late 2013 rMBP and the new Mac Pros.