It uses a B85 chipset. On the Intel platforms, only Z-series chipsets are OCable. One way to get more money out of you.
For a PSU, you want a decent one. The second link in my sig is a good reference.
Generally, a single low/midrange GPU you want about 400-450W, and a higher-end one more like 550W. If you want multiple or to use a dual-GPU card, more up in the 750W range. Those are pretty rough estimates, though.