Those those cute little GTX 750's are pretty fast, the Ti version especially. I may suggest selling the 6970 and picking up a GTX 760, no PSU issues along with a big performance increase and PhysX support all in one card.
The GTX 650 Ti is a great little GPU, it is as fast as a pair of GTX 460s in SLI and runs silent with low power draw. With an i3 4330 I can run Skyrim on ultra at 1366x768, very impressive for such a cheap card.
I found myself in the same situation running an i7 860 @ 4.3Ghz with a GTX 780, so far I haven't run into any performance bottlenecks when gaming (Skyrim, Metro 2033, Farcry 3, Max Payne 3, Hitman Absolution). I plan to stick with my first Gen i7 until after Broadwell is released and has any launch bugs worked out, when I say bugs think the Sandybridge launch chipset problem.
I believe H55 based boards do offer some overclocking options in the BIOS but that all depends on what Asus enabled on your model. If you can find a cheap used P55 based motherboard you will likely be able to overclock the i5 to 4.0Ghz without too much of a fuss and that would eliminate almost any bottleneck with the GPUs mentioned. My primary gaming rig has an i5 750 @4.0Ghz and I am looking at a GTX 780 (non-ti edition) as an upgrade from a 1Gb Radeon 6950, if there is...