AMD Launches “Phenom X2”: AMD Athlon X2 7750 Black Edition Review

Stars (K10) microarchitecture employed in Phenom X3 and X4 processors has finally made it to dual-core CPUs. So, the new Athlon X2 got all the advantages of their elder brothers including shared L3 cache. Nevertheless, these intriguing newcomers will hardly be able to fix AMD’s current market standing. Our today’s article will reveal why.

by Ilya Gavrichenkov
12/14/2008 | 04:26 PM

If you are reading this review, it means you still have believe in AMD Company and hope that they haven’t given up their desktop market share completely. You have high hopes for AMD’s ability to suddenly release a product that will impress the computer community with its performance, overclocking potential, power consumption or some other positive features. These are exactly the feelings we have lately every time we get our hands on the new processors from this manufacturer. Although none of the AMD processors released over the past two and a half years have proven up to all our expectations, we still remember the success of K8 microarchitecture very well, when there was simply no worthy competitor out there. So, we are still very enthusiastic about the new AMD solutions and that stimulates our search for their indisputable advantages and strengths. It is our sincere enthusiasm that explains why you often see something like that in the conclusions to our recent AMD CPU reviews: “taking into account this and that and making a few allowances, we can conclude that the new AMD processor may be of interest to a certain user category”. Actually, AMD new products have definitely proven one thing to us that the company specialists responsible for pricing and positioning are very down to earth and haven’t lost their feel for reality. Athlon and Phenom processors are extremely inexpensive and sometimes you can really save some cash if you decide on an AMD CPU over a competitor solution.


AMD once again decided to play this very strong card. Today they are announcing new dual-core processors in their Athlon X2 family. They stand out due to the fact that they belong to a new 7000 series. Although, the today’s computer community still pins most of its hopes over the upcoming launch of the new Phenom II X4 that will finally work at competitive frequencies due to the long-awaited transition to 45nm production process, AMD decided to fire a “warning shot” in the budget segment before launching their new flagship solution.

So, today we are going to talk about new budget dual-core processors. AMD decided to oppose them to the pretty popular Pentium Dual Core CPUs from Intel. The new processors from Athlon X2 7000 series are in fact not as simple as you may think they are: they belong to remarkable Stars (K10) microarchitecture. In other words, the microarchitecture that has been used in quad- and triple-core Phenom processors has finally arrived into dual-core CPUs. As a result, new Athlon X2 7000 will acquire L3 cache, HyperTransport bus with increased bandwidth and a bunch of other microarchitectural improvements. But on the other hand, Athlon X2 7000 series will inherit all the issues from the 65nm Phenom CPUs leading to low clock frequencies. This dualism makes the new processors extremely interesting for us.  The main question e will try to answer in this article is the following: have the new Athlon X2 become better than the old ones and will they be able to successfully compete against the refreshed Intel Dual Core CPUs on 45nm Wolfdale-2M cores?

Two Is Four Minus Two

Before we get to know the characteristics of the new Athlon X2 7000 from the Stars class, let us say a few words about the prerequisites for their arrival. The thing is that these prerequisites are not so evident: this is not the unification with the Phenom processors. The launch of Athlon X2 7000 series will not mean that the Brisbane based models have to go. On the contrary, these two families will coexist. Moreover, according to current AMD roadmap, Athlon X2 from the old 5000 and 6000 series will remain in the market even longer than the today’s newcomers. Therefore, we see the main reason for the new Athlon X2 7000 series to appear as AMD’s desire to get rid of the quad-core dies production scrapping. There is in fact indirect proof to this fact: the new Athlon X2 7000 are based on the same semiconductor die as the triple- and quad-core Phenom processors.

However, refreshing the dual-core processors lineup by introducing more up-to-date architecture into it may also be a way of making dual-cores more popular. It is no secret to anyone, that there haven’t been any changes in Athlon X2 family for quite a while now. As a result of no action in this segment on AMD’s part, these processors have little by little moved into Budget market sector. And regular dual-core production announcements from Intel have helped this process tremendously.

Anyway, AMD chose the simplest approach to creating new Athlon X2 7000 series processors: they used a standard quad-core Agena die from Phenom X4. Just like Phenom X3 (Toliman) processors are built from Agena with one disabled core, the new Athlon X2 7000 (codenamed Kuma) are built from the same Agena with two disabled computational cores. In this case, however, it would seem more logical to name the new dual-core processors Phenom X2, but AMD marketing specialists base their decisions not that much on logics, but on how well the trademark is recognized by the community.

Therefore, we shouldn’t expect anything really new from the specifications of the Athlon X2 7000: everything there must be quite predictable and transparent. To prove it let us offer you a table comparing side by side the characteristics of the existing AMD processors with Stars (K10) microarchitecture:

So, Athlon X2 7000 has fewer cores compared with Phenom, however, it didn’t affect the 2MB L3 cache, the HyperTransport bus frequency or the typical heat dissipation. It is actually not surprising at all, since Phenom and Athlon X2 7000 are based on identical semiconductor dies. The only thing that really catches your eye when you look at Athlon X2 7000 specifications, is the clock frequencies. The CPUs from the new series will have higher clock speeds than triple- and quad-core Phenom processors. However, the difference is still not very dramatic – only 100MHz. They may have been able to increase the clock frequencies by that number without raising the TDP due to fewer operational cores in the new processors.

The Athlon X2 family on Stars (K10) microarchitecture currently includes two models: Athlon X2 7750 Black Edition working at 2.7GHz and featuring an unlocked multiplier and Athlon X2 7550 working at 2.5GHz. They will launch Athlon X2 7450 with 2.4GHz clock speed a little later. The first two processor models will be priced around $70-$80, which means that they will be positioned rather strangely. The thing is that being positioned as competitors to Intel Pentium Dual Core, they fall into the same price range as Athlon X2 processors on K8 microarchitecture. So, Athlon X2 7000 models will be also competing against AMD’s own previous generation CPUs. At least from the pricing standpoint.

I would like to draw your attention to one more curious fact. The model numbers of the new Athlon X2 7000 series processors all end with “50”. According to AMD’s own rules, it means that they belong to B3 processor stepping that is free from the notorious “TLB-bug”.

Testbed Configuration

Now that we have checked out the specifications of the new processors it is time to test them in practical experiments. Today we are going to compare new Athlon X2 CPUs against the old solutions of the same name as well as against their direct competitors from the Intel Pentium Dual Core family. As a result, we used the following hardware components to build our test platforms:

Kuma vs. Brisbane

To test the new dual-core processors on Stars (K10) microarchitecture AMD provided us with an AMD Athlon X2 7750 sample – the top model in the lineup. The CPU looks exactly like other Socket AM2+ processors. Only the marking gives away its real origin:

First of all, you can notice that although the previous generation dual-core CPUs were marked with “AMD Athlon 64 X2” engraved on the heat-spreader, this processor only has “AMD Athlon” left. Secondly, the processors with Stars (K10) microarchitecture also have a different line in the marking that states the new model number, 2MB L3 cache and the use of the new die.

By the way, since the new Kuma processors use 7000 series numbers, AMD ends up with a very fine naming system for the new generation CPUs. 9000 series is used for quad-core processors, 8000 series – for triple-core ones, and 7000 series – for dual-core ones. However, the upcoming launch of the new Phenom II X4 family, will ruin this logical harmony.

But let’s get back to our today’s hero, AMD Athlon X2 7750. It works at 2.7GHz nominal frequency, which is reported by the diagnostic utilities:

Screenshots also reveal other information about the features of the new AMD Athlon X2 7750. The total CPU L2 cache is 1MB (512KB per core) and shared L3 cache is 2MB big - the same as by the Phenom CPUs. I have to remind you that CPUs on Stars (K10) microarchitecture have their L3 cache memory and memory controller working at their own frequency. In this case it is set at 2.0GHz, like by the fastest Phenom X4 processors.

AMD Athlon X2 7750 CPU is the top model among the new dual-core processors. We specifically stress this fact for you, because the clock speeds of the previous generation Athlon X2 processors on Brisbane core range from 2.7 to 3.1GHz. In other words, the new Kuma processors are inferior to their predecessors in clock frequency, however, it doesn’t prevent AMD from positioning them one step above Brisbane. This is possible due to a number of indisputable advantages that you can see by simply comparing the processor families side by side:

In fact, there are quite a few differences. The new processors support SSE4A instructions, faster HyperTransport bus and faster DDR2-1066 SDRAM. But at first glance it seems that the most important advantage of Kuma over Brisbane that can affect the actual performance is L3 cache-memory. Speaking about the advantages of the new processors, we shouldn’t forget that Stars (K10) microarchitecture boasts a number of improvements hidden deep in computational cores. Due to these improvements the CPU can process more instructions per cycle.

To back up these statements we compared the performance of the new AMD Athlon X2 7750 processor against the previous generation Athlon X2 5200 working at the same 2.7GHz frequency:

As you can see, K10 microarchitecture gives Kuma processors a serious advantage over the predecessors working at the same clock speed. This advantage makes about 15%. In some applications that work a lot with large L3 cache memory of the new CPUs, the performance difference reaches 20-25%. So, not very high clock frequencies of the new Athlon X2 7000 processors shouldn’t discourage you at all: other strengths of the microarchitecture make up for the not very high clock speed.

Nevertheless, looks like we cannot really state that the performance of the dual-core AMD processors has got to a new qualitative level. However, only fully-fledged test session will be able to confirm or deny this assumption. Therefore, let’s get down to it right now.


General Performance

To estimate the general processor performance we resorted to a popular PCMark Vantage benchmark that emulates several scenarios with workload typical of home desktop systems:

Overall we can say that AMD Athlon X2 7750 and 7750 processors do not set the Thames on fire. While the top model shows comparable speed to that of the top Brisbane processor, - Athlon X2 6000, the results of the Athlon X2 7550 get lost on the diagrams among the columns representing previous generation processors.

As fir the statement made by AMD marketing department saying that new Athlon X2 compete against Intel Pentium Dual Core, it is generally correct. Athlon X2 7750 and 7550 outperform Pentium DC E2220 built on 65nm core and the top model of the two also outpaces Pentium DC E5200 on the new Wolfdale-2M core. So, according to the results in PCMark Vantage, Athlon X2 7750 seems to be running approximately as fast as the recently announced Pentium DC E5300.

3D Games

As you know, games are among those applications that get significantly sped up when there is larger cache-memory available. Therefore, new Athlon X2 7750 and 7550 processors based on Stars (K10) microarchitecture enhanced with 2MB L3 cache outperform their predecessors working at significantly higher clock speeds. They look pretty good even against the background of Intel Pentium DC. So, Kuma CPUs may become a reasonable choice for inexpensive gaming platforms.

Media Content Encoding

If we disregard the MP3 encoding results that are barely dependent on the memory subsystem performance and cache-memory size, Athlon X2 7750 and 7550 processors may be called a truly worthy continuation of the dual-core AMD processors lineup. New CPUs from the Kuma family easily outperform all Brisbane based processors with DivX and x264 codecs. Nevertheless, we can’t say that the new Athlon X2 processors managed to surpass the competitors from the Intel camp. They are faster than Pentium DC E5000 series processors only when x264 codec is involved, falling far behind in all other tests.

Other Resource-Hungry Applications

The top Kuma CPUs render almost as fast as the top Brisbane processors working at 400MHz higher clock frequency. As a result, Athlon X2 6000 and Athlon X2 7750 perform practically identical to Intel Pentium DC E5300.

The new Photoshop version, CS4, turns out not the best application for the new AMD CPUs. And although the new Athlon X2 processors demonstrate higher performance raising the bar for the dual-core AMD solutions in this application, they are still dramatically behind Intel products.

However, Athlon X2 7750 and 7550 can definitely please us with their speed during archiving. Thanks to L3 cache memory, they manage to outperform not only their predecessors but also Intel competitors.

Power Consumption

To make sure that you get a complete picture we also measured the power consumption of our test system (without the monitor) built around the new AMD Athlon X2 7750 processor. We decided to compare these results against the power consumption of other platforms with similar performance but built with CPUs on different microarchitectures. These processors will be AMD Athlon X2 6000 and Intel Pentium DC E5300.

The systems were configured in exactly the same way as during our performance tests. Enhanced Intel SpeedStep and Cool’n’Quiet 2.0 power-saving technologies were activated. The CPUs were loaded using Prime95 25.8 utility.

The actual results correlate perfectly with the theoretical data. The previous generation Athlon X2 6000 processor on Brisbane core that features 65W TDP, seems to be much more power-efficient than its successor, AMD Athlon X2 7750 with 95W TDP. It means that the “performance per watt” coefficient is not among the strengths of the today’s newcomer. In this respect, the absolute leader will be Intel Pentium DC E5300: a platform based on this CPU consumes less power under load than an AMD Athlon X2 7750 based system requires in idle mode. Therefore, if you care about your electrical bill or need to build a quiet system, dual-core AMD processors on Stars (K10) microarchitecture may not be your choice.


Although dual-core Athlon X2 7000 processors are based on the same B3 processor stepping as the contemporary quad-core and triple-core AMD CPUs, we should pay special attention to their overclocking potential. As you know, processors with fewer cores working simultaneously dissipate less heat, which, theoretically, may open additional opportunities for successful overclocking.

Athlon X2 7750 processor we tested within our overclocking investigation belongs to the Black Edition series, so it features an unlocked clock frequency multiplier, just like other processors of the same sort. It makes checking out its frequency potential much easier. For our experiments we used a Zalman CNPS9700 LED air-cooler and increased the processor Vcore from the nominal 1.3V to 1.45V. in these conditions we managed to push its frequency to 3.3GHz without losing stability.

Frankly speaking, we were very pleasantly surprised with this result. Triple- and quad-core Phenom processors using similar cores cannot boast similar overclockability in identical testing conditions with air-cooling involved. In this case, however, we managed to increase the processor frequency by 22% above the nominal, which is not bad for the top product in the family.

Therefore, Athlon X2 7000 processors seem to be a much better choice for overclockers than the previous generation Athlon X2 CPUs. The latter processors are unable to demonstrate similar performance when overclocked to their maximum. However, at the same time we shouldn’t forget that Intel CPUs from the same price range are capable of much more impressive overclocking by over 50%. So, despite the indisputable improvement, we can’t expect new dual-core AMD processors to become widely accepted among computer enthusiasts.


How did AMD benefit from introducing contemporary Stars (K10) microarchitecture into their dual-core CPUs? According to the results of our today’s test session, we tend to believe that the primary reason was to make good use of the triple- and quad-core production scrapping. Objectively speaking, new Athlon X2 7000 series processors will hardly be able to improve AMD’s market standing at this time. The thing is that even though the top Athlon X2 7750 from the Kuma generation turned out faster than the top Brisbane CPU, the advantage is not very significant overall. On average the improvement makes only 3-5%. Moreover, other Athlon X2 7000 series models will not be able to offer any improvement over the already existing Athlon X2 from 5000 and 6000 series.

However, so far it is enough for dual-core AMD processors to retain certain parity in terms of performance with the competitors from Intel – Pentium DC. And although Intel has recently moved them to new 45nm cores, Athlon X2 7750 CPU remains a worthy rival not only to Pentium DC E5200, but also to the newer Pentium DC E5300.

At the same time all other consumer qualities of the new Kuma processors cannot stand any criticism. Athlon X2 7000 series made from Phenom CPUs consume a lot of power and are barely promising from the overclocking standpoint. Therefore, we can only recommend the new CPU from AMD with a number of allowances and comments to take into account.

Nevertheless, Stars (K10) microarchitecture has a lot of improvements compared to K8 microarchitecture, so the new dual-core CPUs working at the same frequencies as the old ones perform much faster than the previous generation CPUs. But, just like with Phenom processors, AMD suffers from the use of old production process. Unfortunately, Athlon X2 7000 have the same problem as the Phenom CPUs: the combination of low frequency potential and high power consumption do not let us see the progress that we could have seen otherwise. Therefore, we are very excited about the upcoming Phenom II X4 CPUs that will use new 45nm core. We really want to hope that the long-awaited transition to finer and more contemporary production process will help AMD overcome its stumbling stone and release highly competitive and promising solutions.