Edit: The GTX 660Ti features 1344 shaders, 192bit bus and the same clocks as mentioned below. As a consequence of that the GTX 660 will probably feature 1152 shaders since it is a lower card, the same clocks as below and a 192bit memory bus.
We brought you the news only a few days ago that the GTX 660Ti would be identical to a GTX 670 except with a 192bit instead of 256bit memory interface. Well it appears that particular source was slightly wrong. The latest screen shots of a GTX 660Ti and GTX 660 GPU-Z show that both the cards feature 1152 CUDA cores, not the 1344 previously anticipated for the GTX 660Ti. Both the GTX 660Ti and GTX 660 are based off the same GK104 GPU that the GTX 690, GTX 680 and GTX 670 are made from, except these particular GK104 cards come with more CUDA cores fused off.
The GTX 660Ti will feature 1152 CUDA cores across a 256bit memory interface whilst the GTX 660 features 1152 CUDA cores across a 192bit memory interface. Clock speeds for the cards are identical too, 980MHz core, 1033MHz boost and 6GHz memory. The GTX 660Ti is lavished with the full 2GB of GDDR5 whilst the GTX 660 gets short changed slightly with just 1.5GB.
The GTX 660 features a TDP of just 130W whilsts the GTX 660Ti TDP is expected in the 150W region.Pricing is not known yet but sensible estimates can be made such as around £240 for the GTX 660Ti and around £180 for the GTX 660.
The GTX 660Ti stock cooler has also been pictured courtesy of Expreview and it looks remarkably similar to the GTX 670.