Most current generation Phenom IIx2 / Athlon IIx2 / x3 models can be unlocked to full quad-cores, but it is a chance operation as AMD has stopped binning higher models as yields have improved over-time and such tactics are no longer viable OR profitable.
For motherboards I'll recommend ASUS, because all models [even SB 850] can use Advanced Clock Calibration and unlock the processor through a BIOS patch, same is not the case with competing models [from Gigabyte / MSi] as they need a SB 710 compulsorily for unlocking a processor, here are other links that'll shed more light on the same --
A very rare chance to unlock that proccy otherwise it is really good processor and there's a few differences in performance x2 560 vs x4 955 and best luck....
