I have an Early 2011 MacBook Pro with a Thunderbolt port. I just bought an HP ZR2740w 27" LCD monitor, 2560x1440 pixel resolution. This monitor uses the same IPS panel as the Apple Cinema Display. The monitor came with a DisplayPort cable. I had to buy a separate MiniDisplayPort to DisplayPort adapter. Setup 1: This works. My father's Mid 2009 MacBook Pro with MiniDisplayPort (not Thunderbolt, they didn't have Thunderbolt yet) --> MiniDP to DP adapter --> DP cable that came with monitor --> Monitor. This works, the MacBook auto-detects the monitor and drives it at full resolution. Clearly, the adapter, cable, and monitor all work. It looks beautiful. Setup 2: Exactly the same, except remove my father's MacBook Pro and put in MY MacBook Pro, which is Early 2011 model. This does not work. When I plug in the monitor, the MacBook Pro goes dark for a moment, but no image ever appears on the monitor. Why does my father's machine work and not mine? How can I get my MacBook Pro to drive this monitor? I really don't want to use the dual-link DVI adapter, it is big and ugly and expensive. My father's machine (works): MiniDisplayPort OS X 10.8 Mid 2009 model MacBook Pro My machine (doesn't work): Thunderbolt (should be backwards compatible with MiniDP, though) OS X 10.7 Early 2011 model MacBook Pro Do I need to buy a different adapter for my MacBook? Or a different cable? Do I need to install drivers? Thank you in advance for any help.