BE are great chips!
My old x2 550 BE is an absolute corker. Not only will the other 2 cores unlock but the whole kit and kaboodle will happily run prime overnight at 3.4GHz . No extra voltage applied either. Core 0 and Core 1 are stable up to 3.7 but 2 & 3 stop after 3.4
No idea what it failed (10% overclock on "failed" cores cant be a reason - surely?) on to be sold as an X2 but whatever it is, I havent found it yet!