You'll need ~2.3V for the Crucial's to run em at 1200MHz. If you run your system with an 220MHz ref HT the ram is running at ~1170MHz so the max 2,25V for the ram might not be enough.

Pluged an 5000BE in the M3A yesterday. Expected 100-200MHz more than with the BE2400 but they both to out at around 3.3GHz with 1.5V.
Gonna check the voltages the 5000BE needs for 2.3GHz now.