Ya, I got to 4.8GHz but didn't try to go further really... I was focussing on bclk, CPU vCORE, and CPU PLL to try to alleviate the cold bug. If I can't get past the cold limits, it isn't worth running.
CBB was at -75C, CB was at -108C. I only tried CPU PLL between 1.8-1.85V, and only did bclk between 105-107MHz. I tried wpriming and similar things to get the CPU/board as warm as possible while I pulled down temps, but it had no effect on CB/CBB.
Next attempt, when I find time, I will be trying bclk up to 115MHz or more, and CPU PLL between 1.65 and 1.95. Between these changes, I should be able to find something that changes where the cold bugs hit at.
Everything else is set properly for LN2, and CPU vcore appeared to make no difference with coldbugs - I tried vcore from 1.0V to 1.7V.
If the cold bug doesn't go away, I'll be selling the chip and going back to microcenter for another try. I think its just a matter of finding the right settings, but my first impression of IB was not what I expected from what I've heard. It is certainly not like PHII... Almost impossible to get those chips to cold bug, and you have to really apply some tricks to get around the cold bugs on IB.