I got 5,033Mhz out of mine and stopped there. I was just using a CM Hyper 212 Evo in push/pull config. It was a stable clock but, once I got past 4.8Ghz it needed a significant voltage increase (1.42 - 1.536) for that last 200 Mhz. The temps strangely only went up about 3C average and 5C under full load after about an hour compared to it at 4.8Ghz. Peak temps were 62C after 90 minutes of IBT @ 5Ghz.
I'm sure with an H80i or better, 5.2Ghz might be possible. Maybe more on a suicide run.
As for a video card, on my system, a 7870XT @ 1200 core / 1600 memory (should be between a GTX 660Ti and GTX 670 in performance) would slightly bottleneck on a stock FX6300. Turn it up to 4.6Ghz and it stopped becoming an issue.
My 3DMark Vantage runs:
FX6300 @ stock - score 20978 -
http://www.3dmark.com/3dmv/4649590
FX6300 @ 4,661 - score 24036 -
http://www.3dmark.com/3dmv/4643604
FX6300 @ 5Ghz - score 25082 - http://www.3dmark.com/3dmv/4649609