I can choose between building a new system around a 4770k Haswell or get a Titan. Currently running i7 920 OCed to 3.6 and a 680 2GB. I game at 2560 x 1600 on a single 30". I play the FPS games mostly.
Wait until GTX780 drops. If it's $599, I think it's worth it to get 2x GTX780s for 2560x1600 than a single $1k Titan. If a single Titan is about 50% faster than your GTX680 at 1600P, then . Your CPU is the last thing you need to worry about.
Check out this review @ guru3d. At 1600P, in FPS games, the Titan is the limiting component with a 1st gen i7 Nehalem @ 3.8ghz:
http://www.guru3d.com/articles_pages/geforce_gtx_titan_review,13.html
I think you can push that 920 to 4.0-4.2ghz as well. I think you can ride the wave to Skylake as Haswell's early performance seems to be underwhelming to say the least.
A stock 4770K will be about 30% faster than your OC'd CPU.
Na-a. The performance increase from i7 920 @ 3.6ghz with a GTX680 to i7 4770K @ 5.0ghz with the same GPU at his resolution will be less than 5% in most FPS games, if that. The
Titan is a bottleneck when paired with a 1st gen i7 @ 3.8ghz at 1600P. There is no way a GTX680 will benefit from Haswell's performance increase in a linear fashion you described since the 680 is a good 40% slower at 1600P than the Titan. You'll be GPU limited in 95% of games.
At 1080P, i7 920 2.8ghz can give you 75 fps in Metro LL, but at the same resolution with AA, Titan gets only 44 fps!
At 1600P, it's a slaughter.
The CPU is practically a non-factor for his chosen genre and resolution. Buying i7 4770K + new mobo is throwing $ into the toilet when the GPU is the most limiting component. Intel's marketing machine for SB/Haswell can't hide the fact how amazing i7 920 was.