No, the Phenom II CPUs only officially support 1333MHz, but can be pushed higher. In terms of performance though, there is very little difference between high speed and low speed RAM.
In terms of architecture, the Phenom II X6 comes with 3MB L2 cache instead of Phenom II X4's 2MB, and two extra cores, with TDP ratings of 95W for the lower end Thubans, and 125W for the higher end Thubans.
IIRC, Thuban was based more on the 'Istanbul' Opteron.
But how can it be pushed higher?a little detail or how.....