ZOTAC launched one more GeForce GTX 660, the Thunderbolt Edition, and that has absolutely nothing to do with the Thunderbolt interface. You will get a non-reference design PCB and updated cooling solution. The cooler may look like yet another aluminum fin stack ventilated by two fans, but it's a massive aluminum heatsink, with heat-transfer bolstered by three copper heat pipes.

The cooler features what ZOTAC calls "EClean." Simply put, EClean is a mechanism with which you can easily detach the cooler shroud on which the fans are mounted, by pressing a retention notch, and sliding out the shroud that's suspended on rails, on the main heatsink reports TPU:

Removing the shroud lets you clean the heatsink. Innovations aside, the GeForce GTX 660 Thunderbolt Edition from ZOTAC sticks to NVIDIA reference clock speeds of 980 MHz core, 1033 MHz GPU Boost, and 6.00 GHz memory, leaving headroom for users to overclock on their own. It features 2 GB of GDDR5 memory across a 192-bit wide memory interface. Based on the 28 nm GK106 silicon, the GeForce GTX 660 packs 960 CUDA cores. The card draws power from a single 6-pin power connector, display outputs include two DVI and one each of HDMI and DipsplayPort. ZOTAC did not release pricing information, but we know for sure that this one (like most other innovative graphics card designs from ZOTAC) is reserved for Chinese buyers.

Via TPU via Expreview

ZOTAC GeForce GTX 660 Thunderbolt Photos