Looking at a similar attitude in the context of a P2720DC with a MacBook Pro. I would add that I'd be fine, if Dell said: "We don't support that setup; it's not working.". Instead, I get the go-to-the-Apple-forum response. I did this, no help of course. An email from Dell support suggested that my monitor has a defect. But that, too, isn't confirmed by anyone. Latest state: They seem to be waiting out my return period before responding further. They must have some experience connecting their monitors to Apple hardware, no!?? Either it's supposed to work -- or not.