Have been testing with x16 Uncore until now, but since the Uncore is unloked and 32nm has introduced the Uncore>=1.5xRAM rule, so why not trying x15 Uncore?
It got right into BCLK221 with VVT=1.30v

RAM x8
Uncore x15
I'm still testing and don't know who stable it really is, but so far so good:

@4.2GHZ(221x19) 1.31v, VVT=1.30v