Cheers CryptiK, yeah I'm VERY glad I got that chip back, and even more so that I got a R3E... even if it did mean selling my 17-40L! Looks like a 10-20mV drop from BIOS value is fairly standard across all voltage values.

Current temp here is -2C (and dropping because sun has just set, 5pm) which is why I'm going to be taking my rig back up to the spare room again to test with C-States enabled, possibly with a different BCLK to see if I can do memory/uncore at 1:2 for best performance.

I haven't even started to properly tweak voltages yet so could probably get vcore closer to 1.4v at a push, but anything below 1.45v and I'm happy as a dog with two d!cks.