Four Cores for $100: Athlon II X4 630 and Athlon II X4 620 CPU Review

AMD is going to make a revolution in the inexpensive processors market by launching their new quad-core Athlon II X4 series that will be selling at very democratic prices. The secret of these processors hides in the new 45 nm Propus core that has no L3 cache memory. But how fast are these babies?

by Ilya Gavrichenkov
09/15/2009 | 09:34 PM

Not so long ago new AMD processors from the Phenom II X4 series seemed to be pretty worthy options for systems in the mainstream price range. However, September brought a few significant changes to the processor market. Intel’s recent launch of the LGA1156 platform featuring pretty high-performance Nehalem processors destroyed AMD’s hopes of getting even with Intel in the $200+ segment. As a result, things got back to their natural course: AMD again had to be just a manufacturer if inexpensive processors for budget systems, like a year ago and two years ago.

 

However, it doesn’t at all mean that AMD is going to give up all attempts to increase their market share. Especially since AMD has contemporary 45 nm process at their disposal that allows them to manufacture pretty good Phenom II and Athlon II processors. That is why the company is not going to give in so easily and intends to continue their competition against Intel, but in “lower” market segments, where the microprocessor giant hasn’t yet had the time to introduce their new CPUs on Nehalem microarchitecture. Of course, AMD will definitely resort to their favorite tactics – manipulating the prices in such a way that their CPU could offer better price-to-performance ratio than competitor’s solutions. And today we are witnessing another example of this price war: AMD is launching the cheapest 45 nm quad-core processors priced at $100-$120. AMD’s calculations are very simple here: in this price range Intel offers only dual-core processors, while many inexpensive system users are in growing need for multi-core processors. This need is becoming more acute not only because of the growing number of appropriate software applications that can use multi-core CPUs very efficiently, but also because of the upcoming Windows 7 OS launch that will have special optimizations for efficient work in systems with resources for simultaneous processing of several computational threads. In other words, AMD will try to create a sales hit with very modest means that they have at their disposal: 45 nm cores with rapidly going out of date K10 microarchitecture.

At the same time it is important to understand that Phenom II X4 processors that have been offered so far are barely good candidates for the role of low-cost quad-cores. The thing is that the die size of these processors is close to that of Core i7 CPUs. And it means that the production cost of Phenom II is too high for their successful transition into the lower market segment. That is why AMD designed a new semiconductor die codenamed Propus specifically for the low-cost quad-core CPUs. It has pretty predictable differences from the usual Deneb core employed in Phenom II X4 CPUs: the pretty large L3 cache has been completely eliminated, which should allow the company to drop the price point for their quad-core offerings quite significantly. AMD is going to sell these low-cost processors on Propus core within a special lineup called Athlon II X4.

From the conversations with the company representatives we managed to find out that AMD pins great hopes on the new Athlon II X4. Marketing specialists expect this processor to repeat the success of the legendary Core 2 Quad Q6600. It could be the case, but we should remember that previous generation quad-core CPUs, namely Phenom X4 9000, which were also selling at very democratic prices, didn’t create any commotion among the users. But that was a year ago. Now things are different and the new Athlon II X4 are far not the same thing as the old Phenom X4. 45 nm cores make them not as “hot” and allow setting pretty high clock speeds for them. However, doesn’t the elimination of L3 cache cause dramatic performance drop? This is the primary question that we are going to answer in our today’s article.

Closer Look at Athlon II X4

All AMD processors using four computational cores have always been manufactured within Phenom and Phenom II families. Moreover, the Phenom brand name was also used for some triple-core and dual-core. As a result, the Athlon brand name became a symbol for budget solutions. Obviously, by launching their new Athlon II X4 family, AMD appeals to the same exact associations: Athlon II X4 processors should become the most affordable quad-core CPUs in the market selling for about $100-$120.

As a result, this is what the full list of AMD offering will look like now:

Note that besides the fact that 45 nm AMD processors have different names, the model numbers are part of the single system. For example, quad-core Athlon II X4 processors belong to 600 series, while Phenom II X4 are assigned to 800 and 900 series.

Although Athlon II X4 processors are about 1.5-2 times cheaper than Phenom II X4, they don’t have any serious microarchitectural differences. In fact, Athlon II X4 is the same Phenom II X4 but without the shared 6MB L3 cache and with slightly lower clock speeds. However, it is exactly the elimination of L3 cache seeming not too serious for the performance that has the biggest effect on AMD’s production costs. The thing is that L3 cache memory in Phenom II X4 processors occupies one third of the processor die. Therefore, by physically removing L3 cache from the semiconductor die, AMD can lower the production cost significantly and as a result, reduce the end price on the retail products.

To illustrate everything we have just pointed out above, let me offer you a table summing up the major specifications of quad-core AMD processors. For a more illustrative picture included are also the old previous-generation quad-core solutions based on 65 nm cores.

As we see, AMD managed to reduce the die size of Athlon II X4 processors to 169 mm2. And this is a great result allowing the company to start the price war against Intel without any reservations. The junior quad-core Intel CPUs from the Core 2 Quad Q8000 series consist of two semiconductor dies, each 82 mm2 big. So, the production cost of an Athlon II X4 processor is about the same as the production cost of Core 2 Quad Q8000, which gives AMD a lot of freedom in price manipulations.

At the same time AMD didn’t want to allocate any engineering resources for major core redesign. The “Athlon II X4 = Phenom II X4 – L3 cache” formula is true not only in respect to CPU characteristics. It can also be seen in the core structure. You can see from the photo of the Propus semiconductor die that the part with L3 cache memory has simply been cut off:


Phenom II X4 (Deneb) - on the left, Athlon II X4 (Propus) - on the right

It is absolutely clear from what has been just said that Athlon II X4 processors do not have any undocumented features for L3 cache activation, which a lot of enthusiasts have been secretly hoping for. There is simply no L3 cache that is why in a general case you can’t turn Athlon II X4 into a Phenom II X4.

However, there are a few exceptions. As we learned from one of our AMD contacts, some Athlon II X4 SKUs will be based on Deneb core with a disabled L3 cache that is why if you are lucky, you may still be able to transform your Athlon II X4 into a Phenom II X4. Of course, although Phenom II X4 800 series has been discontinued, AMD still wants to have the opportunity to use partially defective  semiconductor dies left from the production of higher-end processor models. And Athlon II X4 will be exactly this opportunity for them.

Athlon II X4 model lineup will include two solutions with 620 and 630 model numbers. The CPU clock speeds will be 2.6 and 2.8 GHz respectively. Their more detailed specifications are given in a small table below:

AMD plans to launch more Athlon II X4 CPU models. Within the next few quarters the clock speed of the top processors in this lineup will reach 3.0 GHz. There will also be energy-efficient CPU modifications with 45 W thermal design power.

In conclusion to our brief introduction of the new Athlon II X4 processors let us offer traditional screenshots from CPU-Z utility confirming all processor specifications mentioned above:

Note that the CPUID indicator of the new processors has a 00100F52h number that hasn’t been used before, which confirms the uniqueness of these CPU dies and absence of any L3 cache memory in them. The potentially “lucky” Athlon II X4 processors based on defective Deneb cores should have “4” as a model number. This will allow distinguishing them from the other processors based on Propus semiconductor dies.

Testbed and Methods

According to current positioning of the new processors, they do not have any direct competitors yet. AMD claims that Athlon II X4 should be considered as an alternative to the cheapest quad-core Intel CPUs from Core 2 Quad Q8000 series or as a competitor to dual-core Core 2 Duo E7000. However, at the same time Intel quad-core processors are more expensive and as for the dual-cores, it is not quite fair to compare them against quad-cores. Nevertheless, since we don’t have any other options, the new Athlon II X4 will be compared against these particular Intel solutions. Moreover, we also included dual-core, triple-core and quad-core AMD CPUs selling at prices comparable with those of the new Athlon II X4.

As a result, the list of hardware and software components used to build our test platforms included the following solutions:

Core 1/3 Smaller and Performance 10% Lower?

The first question that comes to mind is how important is L3 cache for CPUs on K10 (Stars) microarchitecture. The answer to this specific question will determine the market future of the new Athlon II X4 processors. On the one hand, Athlon II X2 CPUs showed us that the absence of shared cache-memory in the processor cores doesn’t lead to any dramatic performance drops. But on the other hand, it is exactly the shared L3 cache that allows minimizing the latencies during data exchange between the processor cores, so its absence in the new CPUs may make them less attractive. Moreover, in case of Athlon II X2, they partially replaced the eliminated L3 cache memory with a larger L2 cache. However, in Athlon II X4 there is nothing like that. Just like in Phenom II X4, their L2 cache is 512 KB for each core.

To dispel all doubts right away we decided to test several quad-core CPUs on Stars (K10) microarchitecture with the same clock frequency, which are equipped with L3 cache memory of different size. Here is the list of processor cores participating in this test:

All four processors participating in this test session worked at the same clock frequency of 2.8 GHz.

Overall, I can say that L3 cache can have a pretty serious effect on the performance of a CPU based on K10 (Stars) microarchitecture. On average, the performance of a Phenom II X4 with a 6 MB L3 cache is about 10% higher than that of the new Athlon II X4 without any L3 cache working at the same clock frequency. However, as always, cache is not so important for a number of applications, while in others its value is hard to overestimate. For example, in final rendering tasks or video and audio content transcoding tasks Athlon II X4 works just as fast as Phenom II X4 with the same clock speed. But gamers, for instance, should better go with a CPU that has an L3 cache on it, because they can deliver much higher fps rate. Moreover, Athlon II X4 is even slower that the old Phenom X4 in games, even despite all microarchitectural improvements in the 45 nm core, including enhanced branch prediction unit and reduced cache-memory latency.

However, no one is suggesting that we should consider Athlon II X4 as an alternative to Phenom II X4 from a higher market segment. Keeping in mind that Propus processors have not only 1/3 smaller semiconductor die than Deneb, but also cost way less, we can easily forgive the performance lag we see here. Especially, if we assume that they should overclock just as good as their senior counterparts. But let’s not get ahead of our story and first see how well the new Athlon II X4 perform against the other processors from the same price range.

Performance

General Performance

According to the results obtained in SYSmark 2007 that estimates the systems performance in real applications during execution of specific tasks, the top Athlon II X4 processor model can provide about the same performance as the junior Intel CPU with four cores – Intel Core 2 Quad Q8200. This is a pretty good result, because AMD is going to sell their Athlon II X4 at lower prices than Core 2 Quad Q8200. However, you still shouldn’t consider these two CPUs equal, because they perform differently in different tasks. For example, during rendering or video content processing AMD processor can do better, while in office tasks and in applications for creation and processing of 2D raster and vector graphics Core 2 Duo demonstrates higher result.

By the way, in office tasks particularly the missing L3 cache has the biggest effect on Athlon II X4 performance. In these applications these processors yield even to previous generation Phenom X4, which work at significantly lower clock frequencies.

Moreover, it is important to understand that quad-core processors are not always better than their fellow brothers with fewer cores. Dual- and triple-core CPUs from the same price range work at higher clock frequency and that is why they work faster under those types of load that do not parallel well. For example, dual-core Core 2 Duo E7500 quite often takes leadership in SYSmark 2007.

Gaming Performance

As we know, memory subsystem size and speed are very important for contemporary 3D games. Therefore, the obtained results are not surprising at all: Athlon II X4 are far behind their elder brothers from Phenom II X4 family because of the missing L3 cache memory. As a result, even the top Athlon II X4 630 is slightly behind the junior Core 2 Quad CPU.

By the way, the obtained results allow us to make one more very interesting conclusion. Although contemporary gaming applications are better and better optimized for multi-core processors, the triple-core Phenom II X3 looked most preferable in the benchmarks above than the quad-core one.

Performance during Audio and Video Transcoding

Transcoding of any type of media content is the key skill of the new inexpensive quad-cores from AMD. In fact, there is nothing to be surprised about here. In these tasks the entire load is put over the computational resources of the system, while the memory subsystem performance becomes secondary. As a result, Core 2 Quad is defeated even by Athlon II X4 620 in popular video codecs, not to mention the top model of course. Things look a little different in iTunes, but it can be probably explained by the specifics of this program that transcodes audio files only in two threads.

Performance in Applications

During data archiving, Athlon II X4 falls about 10% behind Core 2 Quad Q8200 showing almost the lowest result among all testing participants with the only exception of the dual-core Core 2 Duo E7500.

During Excel calculations things look even worse. This application is well optimized for multi-threaded load and Athlon II X4 processors can only compete against dual-core Intel solutions. If we compare their performance against other AMD processors, these quad-core CPUs without the L3 cache will be about as fast as triple-core Phenom II X3 equipped with an L3 cache.

We can see approximate parity between Athlon II X4 and Phenom II X3 in Adobe Photoshop CS4. But Athlon II X4 is again significantly behind competing Intel solutions: quad-core as well as dual-core ones.

However, during non-linear video editing in Adobe Premiere Pro CS4 the new Athlon II X4 CPUs show brilliant results, just as during simple video transcoding.

The new processors also cope quite well with final rendering. In fact, there is nothing surprising about it: it is just another computational task that doesn’t set any special requirements to the memory subsystem.

Power Consumption

Although AMD used contemporary 45 nm process for manufacturing of their Phenom II X4 processors, the power specs of these solutions didn’t go down to the level of Intel offerings with analogous performance. However, it is still too early to draw any final conclusions yet, because the new Athlon II X4 CPUs feature a new smaller core, which can in fact affect their heat dissipation and power consumption readings.

Therefore, we were especially interested in the results of our power consumption tests of the new AMD processors. The following numbers show the total power consumption of the full tested platforms (without the monitor). During our tests we used 64-bit LinX 0.6.3 utility to load the systems to the utmost extent. Moreover, to ensure that we estimate the power consumption in idle mode correctly we activated all power-saving technologies, such as C1E, Cool'n'Quiet 3.0 and Enhanced Intel SpeedStep.

Unfortunately, even in idle mode Athlon II X4 can’t compete against Intel processors from the same price range and with similar performance, just like other 45 nm AMD CPUs. However, the power consumption difference between the tested systems in idle mode is not big enough to allow us to draw any definite conclusions.

The situation looks considerably worse for AMD under heavy workload. When we tested Core 2 Quad Q8000 processors back in the days, we were amazed at their energy-efficiency. Not that much has changed since then, AMD Phenom II X4 and Athlon II X4 can’t get anywhere close to the same power readings. Despite the fact that Propus processors proved much more economical than their Deneb based predecessors, the difference in power consumption of systems based on Athlon II X4 630 and Core 2 Quad Q8200 reaches almost 50 W!

To get a fuller and bigger picture we also measured the power consumption of Athlon II X4 processors under load, separate from the rest of the computer components. To be more exact, we measured the power consumption along the 12 V power line connected directly to the processor voltage regulator on the mainboard. In other words, this approach didn’t take into account the efficiency of the processor voltage regulator.

The obtained results once again prove everything I have just said. If you are concerned with the power consumption of your system, then AMD processors that do not belong to the energy-efficient type should be taken off the list of choices right away. Although Athlon II X4 also have 95 W TDP, just like Core 2 Quad Q8200, in reality these CPUs cannot be compared at all in actual power consumption. AMD solutions consume about twice as much, but unfortunately, do not offer the same performance advantage. As a result, Athlon II X4, just like Phenom II X4, lose hopelessly to their competitors in performance-per-watt.

Overclocking

AMD processors based on 45 nm cores can usually be overclocked to 3.7-3.9 GHz with air cooling. And this is normally true not only for quad-core but also for dual- and triple-core processors from Phenom II family. It seems logical that new Athlon II X4 CPUs should demonstrate pretty much the same overclocking potential. However, there is always hope for a miracle and in this case it is even stronger due to the fact that Athlon II X4 are based on the new semiconductor die without the L3 cache memory. Therefore, we couldn’t leave out our overclocking experiments this time, too.

All experiments were performed on the same platform as was used for performance tests. We would only like to add that we used Scythe Mugen cooler with a Noctua NF-P12 fan for CPU cooling.

Since both Athlon II X4 processors launched today do not belong to the Black Edition series, they cannot be overclocked by raising the multiplier. To increase the frequency over the nominal values we must raise the clock generator frequency. However, this is very easy to do: new processors work perfectly fine with the clock generator frequency increased quite significantly.

For example, by raising the processor Vcore 0.175 V above the nominal we managed to overclock our Athlon II X4 630 to 3.64 GHz by simply increasing the clock generator frequency to 260 MHz.

Unfortunately, we couldn’t overclock our Athlon II X4 630 any further, because the CPU lost stability. It suggests that the frequency potential of the Propus core for some reason turned out lower than that of the Deneb core equipped with an L3 cache memory.

The results of Athlon II X4 620 overclocking only confirmed our concerns. This CPU overclocked only to 3.57 GHz with the core voltage increased by 0.15 V above the nominal.

To make sure that we cover all aspects of Athlon II X4 overclocking, we decided to test their performance in overclocked mode and compare the results against the performance of overclocked Core 2 Quad Q8200. For this test we increased the frequency of the Core 2 Quad processor to a pretty typical value of 3.4 GHz obtained as 7 x 486 MHz. The opponent will be Athlon II X4 630 overclocked to 3.64 GHz set as 14 x 260 MHz. all other system settings are given in the table below:

As we see, during overclocking Intel processor won a more convincing victory over the new Athlon II X4 than in nominal mode. And this is not surprising at all. Our Core 2 Quad Q8200 processor was overclocked by 45% above the nominal, which is in fact far not the limit for this CPU modification. Athlon II X4 could barely overclock by 30%. In other words, although the overclocking potential of Athlon II X4 is not as modest as that of the old Phenom X4, but it still leaves much to be desired.

Conclusion

Of course, the major advantage of the new Athlon II X4 processors is their low price. Since AMD set the prices for these processors between $100 and $120, they seem very attractive. They are truly the cheapest quad-core CPUs available in the market today that are manufactured with contemporary 45 nm process. And that is more than enough to help Athlon II X4 take over very strong market positions.

However, low price is far not the only great thing about these new AMD solutions. Besides it, the new CPUs are pretty fast, which allows them to perform equally fast with junior quad-core Intel solutions selling at a slightly higher price point. Among the tasks that are a definite strength of the new Athlon II X4 are video processing and rendering applications.

But unfortunately, we can’t disregard the fact that the absence of L3 cache memory is limiting their performance quite significantly in a number of applications. Office work, image editing and 3D games are typical tasks where Athlon II X4 look way weaker than their Phenom II X4 counterparts. And these are the tasks where the new CPUs are defeated by the junior Core 2 Quad solutions. I believe it is a question that only you yourselves can answer judging by your needs and preferences whether low price of the new AMD solutions makes up for their low performance of in all these cases.

As for us, we can conclude that the new CPUs have very adequate combination of average performance and price for the today’s market. Overall, Athlon II X4 could be considered AMD’s small but nevertheless important achievement in the cut-throat competition against Intel, if it hadn’t been for one “but”. A serious drawback these new processors have is their too high power consumption and lower overclocking potential than those of their competitors. Therefore, the combinations of all these factors do not make Athlon II X4 a particular success on AMD’s part. However, we can’t deny the fact that their attractive price will make this CPU extremely interesting for a certain user group, no doubt about that.

Summing up everything we have just said, we can only add that in the current situation AMD picked the right path for their further development. Until they have a new microarchitecture that could compete against Nehalem processors, the only way for them to successfully compete against Intel is the local price war in the lower market segment. Athlon II X4 suits perfectly for the job. The new Propus core developed specifically for these new processors costs much less to make than Deneb core, because it has no L3 cache at all. And it means that with the potential of this new core AMD has every opportunity for further expansion of their inxpensive multi-core processor families, which are going to become even more and more popular with the time.