1) So some quick results from Metro Last Light Benchmark.
GTX 780 Overclocked - Average 30 fps, fan quiet (1084MHz GPU, 75 degrees)
GTX 780 Stock - Average 25 fps, fan quiet
GTX 470 x 2 SLI - Average 19 fps, fans LOUD
Options: Resolution: 5104 x 1050; DirectX: DirectX 11; Quality: Very High; Texture filtering: AF 16X; Advanced PhysX: Enabled; Motion Blur: Normal; SSAA: OFF; My case sure does look empty with only one card, so added some more usb ports on a pci card.
The difference from 19 fps to 30 fps of course is quite noticeable, and in game I have gone from average (using Fraps) 28-32 to 45-50 fps, almost at the sweet spot of 60, but feels much smoother, and of course much quieter and cooler.
2) Bioshock Infinite, cranked up everything to Ultra (after using these fixes:
http://pcgamingwiki.com/wiki/BioShock_I ... g_problems )
and the game runs smooth (45 fps) and has more of a "wow" factor graphically.
3) Crysis Warhead Enthusiast mode runs well.
I say moderately impressed, because $650 should blow me away. In hindsight, I would probably have gone for 2 x GTX 770 at $820. But one card should hold me until Christmas, then can add another 780, and then I will be properly impressed.
Overclock so far stable, played 2 hours each game with no artifacts, problems or fan noise.
P.S. I also do notice that my office is not as hot as before, so will save on A/C.