CPU Guide

The Phenom II X6 - AMD Replies with Six Cores

The Phenom II X6 - AMD Replies with Six Cores

Introducing the AMD Phenom II X6

Introducing the AMD Phenom II X6

Ladies and gentlemen, the multi-core race on the desktop front has now officially moved into 6-core territory. Intel grabbed the headlines with its first 6-core desktop processor last month, the Core i7-980X Extreme Edition, but let's not forget that the first 6-core x86-class processor in the market was the AMD "Istanbul" Opteron. AMD has now brought this server/workstation series to the desktop and intends to launch a series of processors using this 6-core architecture, nicknamed "Thuban" and collectively known as the Phenom II X6. 

Based on the same Phenom II architecture that underpins its current quad-core lineup, Thuban promises six cores on a single die, and is manufactured using GlobalFoundries' 45nm SOI fabrication process. AMD has managed to keep the thermal envelope similar to its quad-cores at 125W TDP for the two models launching today despite the increase in core count, thanks to GlobalFoundries' use of low-k dielectrics materials. Looking at its 2010 roadmap, one can expect even lower, 95W variants by the middle of the year. All of them are compatible with existing AM2+ and AM3 motherboards after a BIOS update, which should be good news for those looking to upgrade their AMD systems.

The core specs should be familiar to anyone who has kept up with AMD's architecture. The company may tout it as a true 6-core solution and there are indeed six distinct processor cores, but the amount of L3 cache on the AMD Phenom II X6 is identical to that on the quad-core  Phenom II. Other staples of the architecture, like the HyperTransport bus and integrated memory controller remain the same as on the quad-cores. The L2 cache has grown proportionally to the number of cores, with 512KB for each. The frequency of the top model, the unlocked, Black Edition AMD Phenom II X6 1090T starts at 3.2GHz while the other, the X6 1055T clocks at 2.8GHz. Below are the specs and pricing details for these new Phenom II X6 processors. 

AMD Phenom II X6 Specifications
Processor Model Clock Speed L2 Cache L3 Cache HyperTransport Bus
Max TDP (W) Retail Price (US$) Availability
AMD Phenom II X6 1090T (Black Edition) 3.2GHz (3.6GHz Turbo Core) 512KB x 6 6MB 2.0GHz 125 $289 Now
AMD Phenom II X6 1055T 2.8GHz (3.3GHz Turbo Core) $199 Now



A Matter of Turbo

You probably have noticed the 'T' in the model numbers and the 'Turbo Core' frequencies listed above. This is AMD's new feature for its Thuban architecture processors - Turbo Core. Feeling a pang of deja vu about this term? You aren't too far off the mark if you're guessing this is related to Intel's Turbo Boost. Turbo Core is AMD's take on Turbo Boost, which if you can remember, is a feature that dynamically scaled up the processor's clock speeds (by a varying number of speed bins) when the application load on the processor is lightly threaded. Idle cores are almost switched off completely and consume close to zero power while the remaining, active cores are bumped up. There is a limit on the total amount of 'overclock' you get from Turbo Boost, which is set by the thermal envelope of the processor.

AMD's version is quite different. For Turbo Core, when three or more of the six cores are idle, the processor's clock speed for the active three cores go up to 3.6GHz for the Phenom II X6 1090T. This is a 400MHz boost for lightly threaded applications. However, unlike the granularity of Intel's technology, which has a varied amount of clock boost according to the number of cores in use (one could get a small increase in clocks for all four cores if the TDP is not exceeded for example), AMD's solution is binary in nature.


So, three cores on the 1090T get boosted to 3.6GHz while the remaining three drop down to its idle state, which is 800MHz on the 1090T along with a corresponding drop in voltage. This move allows AMD to keep the processor within its thermal envelope and which AMD says is a benefit - unlike Intel's Turbo Boost, which depends on keeping within the thermal envelope to improve the extent of the clock increase and is hence partially dependent on your cooling system - AMD's Turbo Core gives a fixed amount based on load and is not dependent on temperature. It also means that AMD's Cool'N'Quiet must be enabled for it to work as intended. 


More importantly for consumers, Turbo Core works in the background (enabled or disabled in the BIOS) and does not depend on software drivers or the OS. It's done completely through the hardware and the usage/load will trigger Turbo Core when it meets its criteria. Finally, Turbo Core will not be restricted to just the 6-core processors. AMD plans to have them on upcoming 'Thuban' quad-cores (essentially 6-cores with two cores disabled), which would have the 'T' designation in its model name as the distinction. Presumably, one would see a 2/4-core Turbo Core split then.