Just FYI, with GPU boost 2.0 nvidia is actually allowing slightly higher vDroop settings on aftermarket cards as compared to reference cards. If i'm not mistaken, they're allowing +37mV across the board with approved coolers, and this also allows the AIBs to adjust the boost parameters to provide longer boosts. If you look at the TPU review of the Windforce 3 GTX 780 and the ACX GTX 780, you'll see the results of the higher voltage and GPU Boost 2.0 parameters - the aftermarket cards get *better* and *longer* boosts than the reference models do. Because nvidia is allowing AIBs slightly more flexibility. No, they're not fully voltage unlocked. But, it is more flexibility.
Nvidia tinkered with GPU Boost 2.0 for the release of the GTX 780. This is why you're seeing many aftermarket GTX 780s outperform even the Titan - while obviously that's not apples to apples - a Titan can be OC'ed as well, but I won't get into that. The point here, is that nvidia is allowing aftermarket cards slightly more flexibility with GPU boost 2.0 and slightly more voltage. Nvidia apparently recognizes that some aftermarket coolers can allow for higher overclocks than the reference, which I think is great.
It isn't a full voltage unlock but it's a nice compromise, IMO. I found the WF3 GTX 780 to be very impressive. Definitely may return my reference 780 (unopened) to exchange it for a WF3.....