The damage isn't too much. Your Voltage Regulator Module (VRM) has a heatsink, however, it only have 4+1 phases, which is sub-optimal. You can still overclock, but I wouldn't push it too far.
As long as the voltages are reasonable, you can probably easily match a FX-6350 speed (3.9 ghz) and not have to worry about it. Personally, I would see how far you can overclock with just stock voltages, and call it good there. You might be able to reach as high as 4.2 ghz.