Technically, the A10-6800k can outperform the 7750 video card.
Remember, by default the 7750 uses DDR3, not GDDR5; only the more expensive models of 7750 ship with that.
You don't need GDDR5 for 720P gaming, you do need it for 1080P and above.
Though the A10-68000k has 384 cores and the 7750 has 512 cores; you the performance does not really scale up in this type of comparison.
Case and point, the A8-5600k is almost as fast as the A10-5800k and has 256 cores; it might be 4 FPS slower on average compared to A10-5800k.
Technically, APU should have a natural advantage to render more FPS as long as memory bandwidth is not an issue.
If you want best FPS for 720P then get DDR 1600 with CAS 7
If you want best FPS for 1080P then get DDR 2133 with lowest CAS.
Don't expect A10-6800k to be sufficient for most 1080p games; will work on many but on low settings.
Expect the APU to hit prime time come DDR4; then there won't be as nearly of a point of getting GPU.
Also the reason the A10-6800k is faster than 7750 besides of all the benefits that it is on 1 die, the cores are not the same as those in 7750; AMD made some updates they are more efficient.
The real question is can you get 20-40% improvement on the A8-6600k, or did AMD mostly find a way to use up the mostly unused cores in the A10-5800k.
There is a 100mhz GPU higher clock which can't hurt.
Overclocking the GPU out of this by another 100-150 mhz would yield enough power for ALL games 720p HIGH-ULTRA settings, 1080p Low - Medium.
When DDR4 comes out, ADD one the the quality.
DDR4 for AMD will hit Q4 2014, and that will be the next AMD motherboard to get.
By 2014, AMD will have nearly completely cough in terms of CPU performance (Floating Point) for games.
Bar none, A10-6800k best/most affordable CPU for DolphinEMU.