I'm running a 2013 MacBook Pro with Yosemite in closed clamshell mode and just purchased an NEC PA272W to accompany my HP ZR24w. Both are connected through the TB daisychain. How they are connected: TB port 1 > ARECA 8050t2 > NEC PA272w (main) TB port 2 > Promise Pegasus2 > CalDigit dock > HP ZR24w (secondary) I'd previously used the HP as my main display connected to the Areca and another monitor connected by a DVI to displayport adapter thorough the Caldigit dock. I don't believe I changed anything else of significance. However, when I now turn off the NEC, it turns off the arrays and puts the computer to sleep. I checked the NEC and don't see anything funky in the menu that would do that. I checked the energy settings and have the computer never sleeping on the power adapter, disabled Power Nap, and unchecked "let disks sleep". I reset the SMC, or at least I think I did. The power plug didn't flicker like suggested. Didn't change anything. I reset the PRAM. That didn't change anything either. If I turn off both displays (ie, not just the secondary HP), it will put the computer to sleep. Help! lol Also, if I let OS X sleep the displays, the computer stays on. It's only if I hit the power button.