AMD's six core CPUs

Overview

The CPU (Central Processing Unit) is the brains of every computer, be it a large desktop or thin-and-light laptop.

Recent CPU architectures from AMD and Intel have centred around increasing performance by adding more cores - mini-brains, if you will - rather than focus on boosting clock-speeds. This approach is also mirrored in the graphics-card world.

Generalising somewhat, budget CPUs are designed with either a single core or two cores working in tandem. Mid-range CPUs have either two or four cores, and the very best have, in mid-2010, six cores.

Following on from Intel, AMD has introduced a flagship series of CPUs, code-named Thuban, which are comprised of six fully-functional cores. Now available from Scan integrated into systems and as standalone parts, this TekSpek explains the technology, positioning, and overall proposition presented by the Phenom II X6 chips.

Hexa-core design

There are two new chips in AMD's high-end arsenal. Let's show how they compare against a slew of other AMD chips in an easy-to-understand table.

The comprehensive table shows that the Phenom II X6 1090T and 1055T are very similar to quad-core models that have been available for over a year now.

AMD has used what it's learnt during the design phase and production of the older chips and put it to use with the six-core models. The manufacturing process remains the same, 45nm, so the 'Thuban' chips have a larger die size and are thus costlier to manufacture.

The good news for enthusiasts is that the new CPUs will work just fine on a wide range of AMD (AM3) motherboards with nothing more than a BIOS update. This means you can upgrade, say, a lower-spec. Phenom II X3 to a Phenom II X6 by just switching the CPUs around.

Technical comparisons

Drilling down, let's compare the six-core Phenom II X6 1090T against the four-core Phenom II X4 955. Both are clocked in at 3.2GHz have a 125W TDP - the maximum wattage the chips can consume when run at default speeds.

The 10-series Phenom's architecture means that a 50 per cent increase in cores - from four to six - is also replicated in an equivalent increase in L2 cache but L3 remains the same, at 6MB. More cache generally leads to better performance.

You may well be wondering how it's possible to add more cores without adding to the chips' power-draw. The six-core chip is able to fit into the same thermal envelope as the quad-core model because AMD has refined the silicon to an extent where each core requires less power to operate at a designated frequency: 3.2GHz in the case of the 1090T.

Turbo CORE and HyperThreading

Phenom II X6 CPUs naming scheme is suffixed with a 'T'. This is important because is denotes that the chips have AMD's Turbo CORE feature, where the CPU dynamically increases the frequency of the chip if the program you're using only requires three or fewer cores to run on.

For example, should a program only use two of the six available cores on a Phenom II X6 1090T, which is often the case, then the CPU will boost those cores from the default 3.2GHz to 3.6GHz.

AMD's Turbo CORE technology is able to boost up-to three cores by 400MHz on the 1090T and 1055T CPUs. The remaining cores, unused, are reduced to 800MHz, enabling the chip to remain within the aforementioned 125W thermal envelope.

AMD's technology isn't quite as refined as Intel's Turbo Boost, where non-used cores are simply turned off, but it does provide extra performance for free in cases where the computer doesn't require all cores to be active.

Adding some context, Intel's mid-range and high-end chips also have an extra feature known as HyperThreading. Put simply, it enables physical cores to be better used when processing information. AMD's Thuban, based on older architecture, does without the benefits of HyperThreading.

Value proposition

Undeniably the fastest desktop CPU in the world, Intel's sole six-core, 12-threaded chip is the Core i7 980X Extreme Edition. Retailing for £825, it is out of the reach of most consumers.

AMD's Phenom II X6 1090T, meanwhile, retails for £240, whilst the slightly slower 1055T can be purchased for £160. The latter, in particular, offers a striking balance between performance and cost.

Summary

AMD's two Phenom II X6 chips provide six-core processing for the masses. Designed by adding more cores to the already-decent Phenom architecture, made possible through advances in manufacturing efficiency, AMD is able to offer the consumer potent chips at mainstream prices. So if you're a power user who likes to run a number of programs in parallel, or need considerable processing power for applications that can execute many threads in parallel - 3D rendering and video editing spring to mind - then AMD's Phenom II X6 CPUs offer an enviable blend of performance and price.