when I tested on flaming blade and bloodrage I couldn't get anything lower then 2:3 working on 32nm. Expecting similar behavior with 45nm walling at 1:2.
I never bothered testing for prime95 since full stability isn't relevant to me on this platform.
For me, 1:1 never worked properly, 1:1 with uncore+1 worked a bit better, 2:3 works fine and much more stable until uncore limited. Below 2:3 I couldn't stabilise 32M, 1M would run just fine, even at 3500+ (never tested on LN2 but not expecting changed behavior.
Keep in mind - until 2 1/2 generations later (Ivy bridge E) nothing intel is able to do 3200+ besides insanely binned Lynnfield and 1366. Trying to find memory that will do 3500+ at 11-15-15-31 is also quite limiting. I'd love to try in a fresh x58a-oc, the socket on mine is badly corroded and the board is generally in rough condition, given I'm the third owner who has ran it multiple times on LN2.
5000 series xeons are all locked to 10x mem multi or even less. 5500 series even has hard lock on uncore multi, can't even change it on most boards.