Thanks I'll probably go with 2 670's but what are so bad about the 680's??? they perform better than almost any other card apart from the 690 and 6990.
Nvidia has always had problems moving to a new fabrication process, I guess the GTX 680 Kepler with full SMX enable makes it extremely difficult to manufacture. The 670's are defective 680's plain and simple they are crippled but still perform very close to the 680 in gaming, that is why the GTX 680 is a huge massive failure. AMD 7970 with 12.7 driver beat Nvidia at most things and are solid overclockers. If you need SLI buy 2 gtx 670's!