Product: AMD Phenom II X6, Asus RoG Crosshair IV Formula
Company: AMD
Authour: James Prior
Editor: Charles Oliver
Date: April 29th, 2010
Phenom II Thuban Specifications

The heart of the AMD Phenom II X6 is the Thuban core. I hesitate to call it new as it doesn't represent a new micro-architecture, but it does represent a remarkable engineering feat - six cores, full speed, in the same TDP as previously seen for four - of the 'same' architecture. The two Phenom II X6 models launching this week are the $295 USD 3.2GHz 1090T and the $199 USD 2.8GHz 1055T, both 125W TDP models with Turbo mode (as denoted by the T suffix on the product name).

AMD Phenom II X6 1090T
AMD Phenom II X6 1090T

Thuban is a native six core design; this is not two quad core dies on a single package with cores disabled. Inside the Thuban core there are a few changes, but nothing really of note technically according to AMD. Below you can see a picture of the 346mm2 die, but don't ask about transistor count - AMD were very coy on this front, as apparently it will be useful info for competitors and disclose information about AMD's IP. Perhaps their competitor will see ~904 million transistors and realize "Damn! That's how you do a hexacore! We should do that!" Oh, wait...

Thuban Die Shot
Thuban Die Shot

3.2Ghz core clock speed is pretty nifty. Certainly higher than the top Opteron 2400 hexacore processors, indicating that the desktop and workstation/server product lines are diverging. Of course, the hexacore Istanbul Opterons have been around a while, have a much lower TDP (75W)) and in fact already been superseded by Multi-Chip Module design Opteron 4100 and 6100 series processors, combining two Istanbul cores to make Lisbon (8-core) and Magny-Cours (12-core) products. Thuban retains the dual channel memory controller seen in other Phenom II processors - no triple channel here.

Cache and Memory

Thuban retains the cache architecture and allocations of previous Phenom II processors, with 128KB L1 (64KB instruction + 64KB data) per core, 512KB L2 per core, and a shared 6MB L3 cache. Built using 45-nanometer SOI (silicon-on-insulator) technology it features a 4000MT/s full duplex 16-bit HyperTransport and an integrated memory controller supporting up to a whopping 21GB/sec dual channel memory bandwidth. Unganged mode disable dual channel but enables simultaneous reads and writes to memory, albeit in different memory modules - important to consider when thinking about multiple concurrent memory intensive applications. Officially the Phenom II X6 supports PC2-8500 (DDR2-1066) and PC3-10600 (DDR3-1333) unregistered DIMM's. AMD's Leo platform and Thuban processors continue to support ECC, in contrast to Intel's desktop processors (Core i5 and i7) which do not.

Turbo Core

Turbo mode is AMD's solution to older, less threaded or scalable applications - some things just need more gigahertz. Analyzing these workloads, AMD research found that boosting three cores to higher clock speeds gives the best balance of performance on demand without excessive power consumption. In fact, Thuban Turbo capable processors are able to maintain the same TDP as at stock. This is possible by use of a new hardware power state, at a higher level than the OS is aware of - a remapping of the hardware and power states.

Power States
Power States

When the motherboard and processor detect that three or more of the cores are idle, they are placed in a halt state and their L2 cache flushed to L3. The three remaining cores are then bumped in clock speed (and voltage, if needed) to give up to a 500MHz increase in core clock. When a load requiring more than the three cores is detected, the cores wake from C-state to resume their last P-state while the active cores clock down from boosted P-state, all while staying within TDP.


While AMD are launching three new chipsets (870, 880G and 890FX), AMD have retained backward compatibility and many existing AM3 and even AM2+ motherboards will be able to support the Phenom II X6 with just a BIOS flash. AMD estimate at launch there will be over 160 AM2+ and AM3 motherboards with support for Phenom II X6 processors, after BIOS update if required.

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