P5B Deluxe BIOS Update leads to strange VCore...

System:
C2D E6600
Asus P5B Deluxe Wireless
4GB Corsair TwinX Dominator PC-6400 4-4-4-12

I flashed the BIOS on my Mobo this evening to the latest version (1004) from the ASUS site - it all went ok, after an initial prompt to re-set optimised defaults.

Now, I did something a little silly, and forgot to change VCore from Auto before changing my FSB from 266 to 400, and my CPU ratio down from 9 to 6 (to stay at the stock 2.4GHz and test stability of the new FSB speed before taking the proc to higher speeds).

When testing temperatures a few minutes later with Prime95, I noticed VCore was up at 1.56V! I swiftly went back to the BIOS and put it back to a more sensible 1.35, which I shall drop to 1.25 tomorrow if my overnight Prime95 run is stable.

So, is the fact that I raised the FSB (but dropped the CPU multiplier) enough to have caused VCore to hit 1.56, or is there something fishy with this BIOS revision?