I HAVE GTX 590 , PHENOM II X6 1090T 4GHZ AND ASUS CROSSHAIRE IV FORMULA AND I WANT TO UPGRADE TO THOSE ( I7 3770K WITH MY GTX 590 AND ASUS SABERTOOTH OR UPGRADE TO 2X MSI HD 7970 OC 1010CORE CLOCK AND I DONT KNOW IF MY CPU WILL BOTTLENECK THOSE CARDS ESPECIALLY I WILL OVERCLOCK THOSE TO 1200 CORECLOCK OR UPGRADE TO I7
AND THEN WHEN I HAVE MONEY I WILL CHANGE GTX 590 TO THOSE WHEN A PRICE CUT
Between your two upgrade options, I would go with the cpu upgrade. You'll notice a performance increase for various cpu intensive tasks with the i7-3770k. With the gtx 590, there's not a lot of room to upgrade there, so spending $1k+ on a barely noticeable improvement is probably not worth it.