I have a stable overclock with most of my cores at 4.8gHz but am having to run 2 cores lower due to temps. My overclock is 100% stable, my power draw at the wall seems low under full load, at idle am drawing 235W give or take and load is 375W which seems low to me. Not that I am complaining, VRM temps are very good and benchmarks seem about right for my overclock. I have clocked per core and have lowered all the voltage offsets, have been trying to make the system keel over, yet it stubbornly remains stable.
I would try to go further but my cooling is holding me back for now, aside from the 2 really hot cores I seem to have a good CPU.