This is my first 1155 board so I cannot really comment on the voltage, although it needed a healthy 1.3v to get to 4.4Ghz on my 2600K
Yeah, maybe I did get a bit lucky with my CPUs, but at the same time, I did buy 13, and keep the two i liked best.
Voltage scaling on these cpus is quite the thing; so varied. However, at the same time, there are only 2 CPUs in Intel's line-up that have HT, so I guess that's kinda expected.
I've had the CPU I'm using for testing in 8 different boards now. It'll do 4.7ghz @ stock volts, on the right board. Although it seemingly requires very little volts, it also doesn't go very much past 5Ghz, with 5.35ghz being the absolute max, and that 5.35ghz is far from stable on air cooling.
My other CPU requires more volts, kinda like yours, but still is slightly better, reaching 5.75Ghz as an absolute max. On stock volts it does 4.4ghz.
It really does seem that the board you use really does affect clocks on the high-end, but on aircooling, it's temps that will set the limit. The power the board provides is going to affect temps too, but I notice only slight difference between boards, a multi or two, between 4.3 Ghz-5.0 Ghz.
That said, I use relatively low voltage for OC'ing in a effort to show you guys what's really going on. Seems to be working, so far.