I want to see if using the display with the desktop area of a 2880x1800 Mac is possible. If push comes to shove, when I get mine, I'll run Windows on it (well, I WILL run Windows on it for games and such at least), but I'd like to know if OS X will work. As I don't have a MBPR yet (haven't even ordered yet), or even a modern OS X machine (unless you count the broken iBook G4 with Leopard on it as "modern", which for these purposes it clearly isn't), I can't really do any experimenting here. But, I'd like to see this solved, hence this thread. Looks like this is the first thing to try (from reading various sources): Set the display to optimal if you're using another setting. Other settings may work, but... best to start there. Install the latest Xcode, then get Graph Tools for Xcode from Xcode>Open Developer Tool>More Developer Tools... Launch /Developer/Applications/Graphic Tools/Quartz Debug, go to Window>UI Resolution, and there will be a checkbox for HiDPI support. I'm expecting this to be checked. If so, uncheck it. If not, report back in this thread, and that will mean that this approach is a dead-end. Log out, re-login. Report what you see, preferably with screenshots. Check the display control panel. If it looks different from normal, screenshots please.