20:06:59: Aero is Disabled
The best thing you can do is enable Aero. Then stream for five minutes of high-action scenes for whatever it is that you're streaming. Then look at the "Duplicated Frames" in your log and make sure they're under 1%. If not, then you should probably drop your framerate to 30fps instead of using 60fps.
With your CPU and bandwidth you should be able to stream with a 1.5x downscale, i.e. 1280x720, I see you tried all kinds of resolutions. If after doing both of the above you still have Duplicate Frames more than 1%, go ahead and drop your resolution down lower, one step at a time, retesting each time.
Finally, there's an advanced tweak you can do to help your stream a little with the CPU you've got (I also use an i7 2600k in my streaming computer): Add the advanced page x264 command "threads=9" or "threads=10" (test to see which value, 9 or 10, has fewer duplicated frames).
Explanation: By default x264 opens slightly too many threads because it thinks Intel's i7 CPUs have 8 cores. They really only have 4 cores, but 8 virtual cores with hyper-threading, and you don't want to load them up with the default number of threads x264 generates for a true 8-core CPU.
