it is, from what i've read on xtreme systems and found with practicing, quite a drop. i've had cpu-z reporting 1.213 under load when set at 1.4+ in bios, but i'm assuming that's a reporting error as it says it all the damn time even if i go up to 1.5v. i don't recall the exact figures from before it started saying 1.213 but i will do some more tests as soon as 3dmark06 is done and report back
-edit-
um ok so 3dmark06 finished and cpu-z is still saying it's 1.213 even idle when it's 1.5 in the bios so something's up with that, sorry. i'll get back here if i manage to get it reporting properly.
p.s. and i'm fairly certain it's cpu-z at fault cos i don't think the E6600 would run on 1.213v at 3.15GHz