Introduction

AMD has had mastery of the budget end of the processor market for some time now for reasons including price/performance, low motherboard prices and platform longevity (they don’t change sockets at the drop of a hat). The only downside has been the sacrificing of the high performance market to Intel (albeit at a much higher price). Last year Intel launched its 6-core processor the i7-980X at the usual "Extreme Edition" price of around a $1000 (or a £1000 if you happen to live in the UK due to sales tax and other historical factors) putting it out of reach of all but a few enthusiasts and professionals in specialized fields such as video editing.

A few months ago AMD launched its own 6-core processors code named Thuban. This week they release the Phenom II X4 980BE (3.7GHz stock and up to 4.1GHz with Turbo Core). This is a Black Edition unlocked processor aimed at enthusiasts and is the fastest AMD cpu to date. Not only are these launching at an aggressive clock speed and with a boosting technology to rival Intel's Turbo Mode, the estimated street price for the Phenom 2 X4 975BE will be $185. We have tested the 980BE and it promise to really shake up the current status quo with performance that in some cases beats the best Intel CPUs available.

AMD are not just marking time until the release of their Bulldozer architecture but are aggressively ramping up clock speeds and pushing down prices to keep market share out of the hands of Intel.

Of more universal interest is comparing the efficiencies of the latest Intel and AMD architecture to compare current and future efficiencies and predict how future trends and architectures will affect performance.

Processor Architecture

With the original Thuban launch we received a new chipset, the 890FX, which promises better performance and greater headroom for overclocking. The board we tested with was the ASUS Crosshair IV Formula.   

SATA-3 is now standard although USB 3.0 still has to be provided by 3rd party hardware (NEC in our case). That will change with native USB 3.0 support when the new Bulldozer chipset is released later this year. Now on to the processor specification:

Each core has 64KB of L1 data and instruction cache and 512KB of L2 cache. 6MB of L3 cache is shared between the cores for a total of 8MB. A 45nm process and manufacturing optimizations keep the processor within a thermal envelope of 125W despite the high frequency. This TDP will be of key importance when we discuss the Turbo Core feature.

The CPU 

This processor is aimed at gamers with a stock speed of 3.7GHz and fully unlocked. We also suspect that the BE processors are cherry picked for the best overclocking headroom but AMD have neither confirmed nor denied this.

The X4/X6 range will fit into a standard AM3 socket (a BIOS update may be required for some motherboards) showing AMDs commitment to platform longevity and ease of upgrading.

We received final shipping product for our testing and not an engineering sample so we are confident that our tests will reflect the actual performance that consumers will experience.

Intel has been using it's Turbo Mode for some time now with i5/i7 processors to boost the speed of one or two cores by a few steps when thermal envelopes allow. The greatest benefit is gained in applications that are not highly threaded and so cannot otherwise fully utilize all available cores. AMD now also have this feature built into their latest range in the form of Turbo Core, which allows for 3 cores to be boosted by up to 500MHz when the other 3 are at low utilization. This is more than was originally expected and is done by cleverly reducing the speed of unused cores to 800MHz and lowering voltage correspondingly while increasing voltage to the boosted cores. This is all done automatically by the processor although some motherboards (such as the ASUS one we tested with) allow the Turbo Core feature to be tweaked independently of the usual CPU adjustments. The net effect of this is to maximise processor performance with any type of application while staying within the 125W thermal envelope.

Overclocking

Traditionally, AMD processors have been more difficult to overclock than their Intel rivals with most users able to boast modest overclocks without exotic cooling.

The 975BE reached 4.5GHz before we decided enough was enough and didn't run stably higher than that although given enough time tweaking more should definitely be possible.

We used a Corsair H50 which gives the benefits of water cooling with the ease of installation of an air-cooled HSF. In terms of cost and performance it is similar to a high end air cooling solution but without the bulky heatsink or noisy CPU fan. Please not that due to the small reservoir on these sealed budget water block and radiator combo systems they should not be used for extreme overclocking and if the processor temperature gets above 70 degrees Celsius it should be brought back down immediately to prevent water turning to steam and permanently “unsealing” the system.

The upshot is that AMDs new processor is a delight for overclockers - particularly poignant given the difficulties Intel users have overclocking the new Sandy Bridge processors.

AMD's new manufacturing process should have overclockers rubbing their hands with glee especially given the price. We estimate that an entire system based around the Phenom II X6 1100T including monitor and budget SSD can be purchased for the price of an Intel i7-980X processor alone.

The Problem with Multi-Tasking

Since this review is primarily about multi-core efficiency it is worth explaining the inherent problems with multi-tasking. This may surprise some readers as we already have supercomputers made up of thousands of Intel or AMD processors and if they did not scale well then research institutions would not buy them to predict climate change, where minerals are buried and so on. The reason they work so well is that it is easy to split millions of operations among thousands of cores. Splitting one thread across multiple cores is actually quite difficult.

The problem involves concurrency, monitors and semaphores and is too involved to go into here although interested readers are encouraged to read the Wikipedia article on “Dining Philosophers” which explains the whole problem in easy to visualize terms. It can be found here.

Until Quantum Computing is viable we will have to rely on programmers making allowances for multiple cores and programming accordingly. Some games and applications are already optimized to a limited degree for multiple cores and theoretically every application will get a boost with a second core, even if just by offloading the usual Windows background processes to the other unused core.

It has been clear for some years that frequencies cannot continue to increase due to manufacturing limits and have remained roughly constant around the 3GHz mark for about 6 years. Instead it seems that the future gains will be attained by increasing the number of cores in a CPU, whether physical or also virtual (as with HyperThreading). Our test will aim to show which architectures are most suited to getting the best out of extra cores, where the bottlenecks are and, hopefully, give an indication of how the architectures will scale in the future as number of cores increase.

Test Setup

All games are tested at the maximum available settings and initially at 1024x768 so we can be sure of hitting CPU limitations before bandwidth or fill rate ones related to the GPU. We selected Far Cry 2 (first person shooter), HAWX (air combat) and Resident Evil 5 (horror) for our tests as they are newish titles that are suited to benchmarking and make most systems struggle.

Were it not for the Sandy Bridge newcomers the AMD processors would be very competitive. Synthetic benchmarks can be useful for examining architecture potential and design bottlenecks but the "proof of the pudding" is always in the real world benchmarks.

The processor multimedia results also scale well although real-life differences will not be as pronounced as this chart indicates. Here the newest AMD "Thuban" processors take a clear lead by virtue of extra cores while the 980BE is beats its closest Intel rival - the i5-2500.

Memory performance tends to vary little little in benchmarks and the real-world impact can be unpredictable depending on the application. Ultimately, the 2000MHz DDR3 of the Intel platform makes all the difference over the 1600MHz DDR3 the AMD systems have.

Everest is a very comprehensive benchmark suite that is set to take the synthetic crown from SiSoft Sandra. We limited our testing to the CPU and FPU benchmarks provided.

CPU Queen is a simple integer benchmark which focuses on the branch prediction capabilities and the misprediction penalties of the CPU. It finds the solutions for the classic "Queens problem" on a 10 by 10 sized chessboard. CPU Photoworx is an integer benchmark that performs different common tasks used during digital photo processing. CPU Zlib is an integer benchmark that measures combined CPU and memory subsystem performance through the public ZLib compression library. CPU ZLib test uses only the basic x86 instructions, and it is HyperThreading, multi-processor (SMP) and multi-core (CMP) aware. CPU AES is an integer benchmark that measures CPU performance using AES (a.k.a. Rijndael) data encryption. It utilizes Vincent Rijmen, Antoon Bosselaers and Paulo Barreto's public domain C code in ECB mode.

Since all of these tests are fully threaded we see a linear increase in performance as number of cores increases. It is worth noting the effect of overclocking to 4GHz - a massive 25% overclock with a commensurate increase in performance. There is no way to match the performance of the new Sandy Bridge processors especially with hardware encryption to boost the AES test.

The FPU Julia benchmark measures the single precision (also known as 32-bit) floating-point performance through the computation of several frames of the popular "Julia" fractal. The code behind this benchmark method is written in Assembly, and it is extremely optimized for every popular AMD and Intel processor core variants by utilizing the appropriate x87, 3DNow!, 3DNow!+ or SSE instruction set extension.

The FPU Mandel benchmark measures the double precision (also known as 64-bit) floating-point performance through the computation of several frames of the popular "Mandelbrot" fractal. The code behind this benchmark method is written in Assembly, and it is extremely optimized for every popular AMD and Intel processor core variants by utilizing the appropriate x87 or SSE2 instruction set extension.

The FPU SinJulia benchmark measures the extended precision (also known as 80-bit) floating-point performance through the computation of a single frame of a modified "Julia" fractal. The code behind this benchmark method is written in Assembly, and it is extremely optimized for every popular AMD and Intel processor core variants by utilizing trigonometric and exponential x87 instructions.

The situation is very different with floating point operations and here the AMD newcomer beats all the Intel processors.

Now for a variety of different games at popular resolutions.

All of the processors can manage playable frame rates at all resolutions with the 980BE nudging ahead of the i7-870 despite being considerably cheaper.

HAWX is readily playable at all resolutions and the AMD newcomer leads the pack here. 

Here the Intel processors manage to pull ahead due to some kind of bandwidth limitation. Even the highly clocked 980BE struggles to exceed 60fps. Given that our GPU results with a Radeon HD 6990 showed CPU limitations at all resolutions, we can conclude that this benchmark is indeed CPU limited with the Sandy Bridge architecture having a few tricks up its sleeve. This game is playable at all resolutions with any of the processors.

Conclusion

AMD are in an interesting position. Their current processors cannot compete at the high end with Intel's Sandy Bridge architecture but rather than just sit tight and wait for the release of their new Bulldozer architecture, they have adopted a number of key strategies.

Firstly by continuing to release fast processors like the AMD Phenom II X4 975 Black Edition they are putting pressure on all but the very top (and therefore expensive) Intel processors. AMD has highly competitive offerings in the midrange and entry segments.

Secondly, by supporting the AM3 socket at a time when their main competitor is changing motherboard requirements at the drop of a hat, AMD provides platform longevity and an easy upgrade path for their consumers resulting in fewer switching to Intel when they do upgrade.

AMD have made a strong play for the high end of the processor market with the release of the Phenom II X6 1100T and 1090T processors. Importantly, they have done this without charging a premium as Intel have been content to do with their "Extreme Edition" price point. The strategy of dominating the low end / mainstream market and using that as a springboard for the high end as they have done in the GPU arena with ATI may be putting them back on an equal competitive footing with Intel - something which can only be good for the consumer. The danger is in getting left behind architecturally and we await the forthcoming Bulldozer architecture refresh for a glimpse of where AMD sees its future.

What then of the Phenom II X4 980BE? If you need to buy or build a new system then performance is on a par with more expensive Intel processors and it will appeal. More so if you already have a socket AM3 motherboard as an AMD 4 or 6 core processor will slot right in. At under $200 we highly recommend it.

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