Thanks, Raja -- that's very helpful. I'm using manual mode, as my 3570k needed only 1.24 Vcc @ 4.7ghz in that mode, whereas in offset the lowest I could get was 1.27 (at 0% LLC), while also keeping the idle Vcc stable. Apparently the VID curve was a little pessimistic for this particular chip.
That experience brought up another question/suggestion -- could a BIOS have 2 offset controls: 1 for Vidle, 1 for Vload, and interpolate in-between?
Thanks again,
David