Reports suggested that AMD was going to release a six-core processor codenamed Thuban sometime next year, and AMD officials have just told Maximum PC that the chip was a done deal.

Based on 45nm SOI technology, AMD’s chip will feature AM3 package, an integrated DDR3 1333MHz memory controller, 3MB of L2 cache, and 6MB of L3 cache. Thuban is likely to be a 346mm2 chip and have a massive 904 million transistors.

The clock speed is not expected to be as high as the quad-core parts, considering the added thermal output from the two additional cores.

AMD officials have also confirmed that it will be backwards compatible with existing AM3 and AM2+ motherboards. “We are all about platform longevity and long-lived upgrade paths,” AMD spokesman said in a sideways ding at its competitor Intel which has a penchant for requiring new sockets for its CPUs.

Thuban is expected to come out in Q3 2010, and very likely to be branded as Phenom II X6.