Inno3D has released a semi-custom version of the GTX Titan, this one sporting Arctic's Accelero Hybrid cooler. It is called the GeForce GTX Titan iChill Black Series. While Nvidia doesn't allow manufacturers to make any changes to the reference PCB design, apparently, manufacturers can still choose to use a different cooler or change the clock speeds.
Arctic's Accelero Hybrid is a cooler that shares the idea from Asus' ARES II card, which has a liquid cooler for the GPU and a fan on the shroud to cool the other components, such as the RAM and the VRM; hence, it's called a hybrid cooler. The unit is also closed-loop and thus maintenance free.
Beyond the custom cooler, the GPU's core speed has been changed. What used to be 837 MHz base and 876 MHz boost is now 837 MHz base and 980 MHz boost. The memory clock speed has remained the same, at 6 GHz, as well as the 2688 CUDA cores, 224 TMUs, 48 ROPs, and the 384-bit memory bus. Since Inno3D can't make any changes to the PCB design, the card also still draws power from a combination of a 6-pin and 8-pin PCIe power connector. Display outputs are also still two DVI ports, HDMI and a DisplayPort.