AMD Phenom II X2 550 and AMD Athlon II X2 250 Processors Review

The transition to 45nm CPU manufacturing process has already created a revolution among triple- and quad-core AMD processors. Now 45nm cores are ready to go into dual-core CPUs, too. But is a finer manufacturing process enough for AMD to offer something interesting in the sub-$100 price range? Our today’s article should answer this question for you.

If you are a regular on our site you may have noticed that there were very few articles about dual-core processors launched within past year – you can count them with the fingers of your one hand. However, it doesn’t mean that we favor the multi-core concept more. On the contrary, every time we can we keep mentioning that the performance of CPUs with two computational cores is more than sufficient for the current stage of software market development. Not so much interest to the “dual-core” market segment may be explained by the fact that it has almost completely ceased developing, since the leading x86 CPU makers focus most their efforts on development and promotion of quad-core solutions in the first place. All activity on the dual-core front has long been limited either to slight increase in the clock frequencies of the existing processor families, or to lowering of their prices.

However, small changes like that have finally produced a good result, which we have discussed in our article called “Inexpensive Dual-Core: AMD Athlon X2 vs. Intel Pentium”. As we learned, dual-core AMD solutions were no longer serious rivals to Intel Core 2 Duo processors and were only competing against inexpensive Intel Celeron processor models. Our tests showed that even relatively new Athlon X2 7000 series processors couldn’t be considered a competitive alternative even to Pentium CPUs on Wolfdale-2M core, not to mention more serious Intel solutions.

Nevertheless, AMD’s current “renaissance” inspired by the introduction and distribution of the new 45nm cores does make a few adjustments to this situation. For example, triple-core Phenom II X3 700 processors proved quite competitive and with a few allowances they can be regarded as an alternative to Intel Core 2 Duo. However, it is obvious that AMD needs several good dual-core offerings performing at a competitive level to secure their position in the mainstream market segment. AMD specialists also understand that very well that is why it was one of the company’s top priorities to launch refreshed processor models on the newest 45nm cores.

So, finally, AMD is filling in the gap in their own product range by launching so long-awaited dual-core CPUs priced between $70 and $120 – one of the hottest and most demanded price-ranges. Moreover, AMD prepared a very pleasant and unexpected surprise for their fans by launching two new generation dual-core processor families at a time: Phenom II X2 and Athlon II X2. The CPUs in the first family are cut-down derivatives of Phenom II processors with more cores, while Athlon II X2 is actually more of an independent product, which is still a little similar to Phenom II in microarchitecture and some other parameters. We are going to introduce to you CPUs from both these families in our today’s review and see if these dual-core solutions can help AMD turn things around.

AMD Phenom II X2

The entire diverse lineup of Phenom II processors is an excellent example of unification. Phenom II X2 500 family we are going to talk about today is the fourth CPU modification based on the same Deneb semiconductor die that was first employed in Phenom II X4 900 CPUs. Moreover, Phenom II X2 seems to be the most irrational use for the initial quad-core die, because in this case two cores are disabled. However, on the other hand, the remaining dual-core CPU with an L3 cache is also a remarkable example of efficient resource utilization: thanks to Phenom II X2, AMD can find good use for dies with multiple defective cores.

This CPU “piece” is called Callisto. It is on one of the edges of the Phenom II genealogical tree: there are no more cut-off modifications of the new 45nm die anywhere on AMD’s roadmap.

As you may easily guess, the new Phenom II X2 500 inherit all the major features from their elder brothers due to the fact that they are based on the same semiconductor die. The primary ones are compatibility with Socket AM3 mainboards and support of fast DDR3 SDRAM. Of course, the new dual-core processors can also be installed into the Socket AM2/AM2+ mainboards, just like all other Phenom II CPUs. In other words, new dual-core Phenom II X2 can be used in the new systems and as an upgrade for the existing ones.

At the same time although Phenom II X2 is a sort of a side product for AMD, the company took the specifications of this solution very seriously. Besides a 6MB L3 cache (the same size cache as that of Phenom II X4 900 processors), these solutions have pretty high clock speeds. The top Phenom II X2 550 processor works at 3.1GHz frequency, which is only 100MHz lower than that of the flagship Phenom II solution – Phenom II X4 955. Moreover, the calculated heat dissipation of the Phenom II X2 500 series processors is lower than that of all triple- and quad-core Phenom II CPUs due to fewer active cores (the only exception are the energy-efficient models). It equals only 80W.

The following table with specifications should give you a better idea of the position the new dual-core newcomers take in AMD’s current Phenom II processor lineup.

We received the top Phenom II X2 550 model for our tests. You can see its specifications in the CPU-Z screenshot below:

1 amd phenom II black edition cpu

As we can see, the utility shows that the codename of our sample is Deneb, which is actually not wrong. But at the same time it is important to keep in mind that AMD has its own unique name for this quad-core die with two disabled computational cores used for Phenom II X2 550 processors. They call it Callisto.

You can also see from the screenshot that Phenom II X2 550 processor belongs to the Black Edition series, i.e. has an unlocked multiplier and hence can be easily overclocked. Considering the price of these processors that will be set at around $102 (according to official information), Phenom II X2 550 may become a good choice for budget overclocker platforms. Especially since new AMD processors based on a 45nm core have pretty good frequency potential.

AMD Phenom II X2 550 is not the only solution in the Phenom II X2 500 family launched today. At the same time AMD is announcing a 3GHz Phenom II X2 545, which will compete against Intel Core 2 Duo E7000 processors just like its twin-brother. However, before we get to comparative benchmarking, let’s take a closer look at another new solution AMD prepared for us today.

AMD Athlon II X2

Judging by the specs, Phenom II X2 500 series processors should be a very good offer for the sub-$100 price range. However, it is fairly expensive for AMD to make these CPUs. Their die size is comparable to the die of flagship Intel Core i7 solutions, which means that Phenom II X2 500 production cost is relatively high. Therefore, it is obvious that Phenom II X2 500 series appeared only because AMD didn’t want to waste defective quad-core Deneb dies. They are very unlikely to use fully-functional dies for these dual-core processors. And it means that AMD doesn’t have the opportunity to supply sufficient volume of Phenom II X2 500 CPUs to the market and they will hardly save the situation with AMD dual-core processors in the mainstream segment.

Therefore, it is not surprising that besides Phenom II X2, AMD is also launching one more CPU – Athlon II X2. Although this processor has similar specifications to Phenom, it is based on a cheaper Regor core. The main differences between Deneb and Regor are right there in front of you: this semiconductor die has only a pair of computational cores and no L3 cache at all, which makes it smaller in size and cheaper to manufacture. From the architectural prospective, Athlon II X2 dies are hardly any different from the Phenom II X2 processors: they use absolutely identical K10 (Stars) microarchitecture. The only modification introduced by AMD engineers is a larger L2 cache of each individual core: its size has been increased from 512KB to 1024KB, which should somehow make up for the absence of any L3 cache memory in Regor.

As a result, Regor die measures, which makes less than half the size of Deneb die. And it is about the same as the die size of dual-core Intel processors from Core 2 Duo E8000 family also manufactured with 45nm process. However, it is important to remember that Intel processors are much more “complex”: they consist of about 410 million transistors, while Regor core has only 234 million of them. That is why contemporary dual-core Intel processors on Wolfdale core have a 6MB L2 cache, while Athlon II X2 CPUs with the die of the same size are only equipped with a total of 2MB L2 cache memory.

2 regor die

The semiconductor Regor die specifically designed by AMD engineers also allowed lowering the heat dissipation and power consumption levels for dual-core AMD processors. Dual-core Phenom II X2 500 based on Deneb core dissipates about 80W of heat, while Athlon II X2 processors on Regor core have 65W TDP. Therefore AMD hopes that the introduction of 45nm process for dual-core CPU manufacturing will allow their new solutions to compete against Intel not only in performance but also in power-efficiency.

At the same time AMD wants to present Athlon II X2 family as a simpler and cheaper solution than Phenom II X2 500. That is why CPUs in this family will work at lower clock frequencies and will also sell for less: for example, the top Athlon II X2 250 model is officially priced at $87, which is $15 less than what Phenom II X2 550 is selling for. However, when you compare the specifications of these two processors side by side, you can’t claim with all certainty that Athlon II X2 yields to Phenom II X2 500 in anything at all. To illustrate this point let’s check out the specifications of the two new dual-core AMD processors side by side. Here they are – Phenom II X2 500 series and Athlon II X2 200 series CPUs:

3 phenom II x2 500 , athlon II x2 200 comparison

In our opinion both AMD solutions belong to the same class of dual-core processors. And the fact that both of them, Athlon II X2 as well as Phenom II X2, are compatible with the new Socket AM3 platform helps promote the new platform in the market. And this platform is going to get even more and more popular, especially since DDR3 SDRAM prices have just dropped and inexpensive Socket AM3 mainboards based on AMD770 chipset start selling freely.

For our performance tests we are going to use a top product in the Athlon II X2 family – 3GHz Athlon II X2 250. You can see the specifications of this particular processor on a CPU-Z screenshot below:

The diagnostic utility we are using at this time is not yet very well familiar with the new Regor CPU core. Nevertheless, it does display all parameters correctly. It is here that you can already notice that Athlon II X2 processor stepping is different from that of Callisto core used in Phenom II X2, thus stressing different origin of the two.

AMD Athlon II X2 Cache-Memory

Taking into account that the only principal innovation in Athlon II X2 processor dies is the modified cache-memory subsystem, we decided to dwell on it a little more. As we have learned before, in our first Phenom II CPU review, AMD engineers didn’t make any changes to the cache working algorithms when they introduced new 45nm process. As a result, cache-memory of Phenom II processors on Deneb core works at exactly the same speed as the cache-memory of first-generation Phenom CPUs. However, Regor core may have some surprises hidden up its sleeve, because its L2 cache is twice as big.

However, despite this fact, the associativity of its L2 cache remained the same: Athlon II X2, just like Phenom II X2, uses L2 cache memory with 16-way associativity. This allows us to anticipate equal performance from the L2 cache of the new Athlon II X2 and Phenom II X2 processors. The advantage of having a larger L2 cache in Athlon II X2 will imply that the data is more likely to be in it.

This is what it looks like in reality:

As we have expected, during the actual tests, we saw almost the same L2 cache performance numbers by Deneb based CPUs and those on the new Regor core. Athlon II X2 memory subsystem turned out a little faster, which is perfectly logical considering that it didn’t have to spend extra resources on searching L3 cache memory for the requested data.

Testbeds Configurations

For our extensive testing of the new dual-core Callisto and Regor processors we decided to compare them not only against the competing Intel solutions but also against their predecessors from AMD, even though they may fall into a slightly different price segment. Therefore, we were working with three different platforms that were configured as follows:

1. Socket AM3 platform:

  • CPUs:
    • AMD Phenom II X3 710 (Heka, 2.6 GHz, 3 x 512 KB L2, 6 MB L3);
    • AMD Phenom II X2 550 (Callisto, 3.1 GHz, 2 x 512 KB L2, 6 MB L3);
    • AMD Athlon II X2 250 (Regor, 3.9 GHz, 2 x 1024 KB L2).
  • Mainboard: Gigabyte MA790FXT-UD5P (Socket AM3, AMD 790FX + SB750, DDR3 SDRAM).
  • Memory: Mushkin 996601 4GB XP3-12800 (2 x 2 GB, DDR3-1600 SDRAM, 7-7-7-20).
  • 2. Socket AM2 platform:

  • CPUs:
    • AMD Athlon X2 7850 (Kuma, 2.8 GHz, 2 x 512 KB L2, 2 MB L3);
    • AMD Athlon X2 6000 (Brisbane, 3.1 GHz, 2 x 512 KB L2);
    • AMD Athlon X2 6000 (Windsor, 3.0 GHz, 2 x 1024 KB L2).
  • Mainboard: Gigabyte MA790GP-DS4H (Socket AM2+, AMD 790GX + SB750, DDR2 SDRAM).
  • Memory: GEIL GX24GB8500C5UDC (2 x 2 GB, DDR2-1067 SDRAM, 5-5-5-15).
  • 3. LGA775 platform:

  • CPUs:
    • Intel Core 2 Duo E7500 (Wolfdale, 2.93 GHz, 1067 MHz FSB, 3 MB L2);
    • Intel Core 2 Duo E7400 (Wolfdale, 2.8 GHz, 1067 MHz FSB, 3 MB L2);
    • Intel Pentium E6300 (Wolfdale-2M, 2.8 GHz, 1067 MHz FSB, 2 MB L2);
    • Intel Pentium E5400 (Wolfdale-2M, 2.7 GHz, 800 MHz FSB, 2 MB L2).
  • Mainboards:
    • ASUS P5Q Pro (LGA775, Intel P45 Express, DDR2 SDRAM);
    • ASUS P5Q3 (LGA775, Intel P45 Express, DDR3 SDRAM).
  • Memory: GEIL GX24GB8500C5UDC (2 x 2 GB, DDR2-1067 SDRAM, 5-5-5-15).
  • Besides the above listed parts, all testbeds also included the following identical hardware and software components:

  • Graphics card: ATI Radeon HD 4890.
  • HDD: Western Digital WD1500AHFD.
  • Operating system: Microsoft Windows Vista x64 SP1.
  • Drivers:
  • Intel Chipset Software Installation Utility;
  • ATI Catalyst 9.5 Display Driver.

I have to point out that we decided to use a fully-functional Socket AM3 platform equipped with DDR3 SDRAM in our today’s test session even though we are testing relatively inexpensive dual-core AMD CPUs. We made this decision because DDR3 SDRAM prices have recently dropped significantly and this type of memory started spreading aggressively over the market. However, we continue testing LGA775 processors on a platform equipped with DDR2 SDRAM, because it is impossible to use high-frequency memory with Core 2 Duo and Pentium processors which bus can only be 1067MHz at the most as a result of specific limitations implemented in the chipsets for them. Nevertheless, during LGA775 processors overclocking when we could use memory faster than 1067MHz, we replaced our Asus P5Q Pro mainboard with a similar solution – Asus P5Q3 – equipped with DDR3 SDRAM DIMM slots.

Evolution of Dual-Core AMD Processors

Dual-core AMD processors have very long history. The first CPUs were made back in 2005 under Athlon X2 brand name. And although it may seem surprising, many modifications of AMD’s dual-core processors that have been manufactured since then are still up-to-date enough and selling in stores. Speaking of these long-living but yet contemporary solutions, we first of all imply Socket AM2 Athlon X2 processors from 5000 and 6000 series that still use K8 microarchitecture and are manufactured with 90nm and 65nm technological process as well as Athlon X2 7000 series processors based on 65nm cores with K10 microarchitecture. Now that Athlon II X2 and Phenom II X2 CPUs on contemporary 45nm cores have joined the gang, it doesn’t mean that old Athlon X2 solutions will immediately disappear from retail. Dual-core CPUs on K8 microarchitecture still remain in the current company price list.

Therefore, it is fairly easy to follow the evolution of dual-core AMD processors: most representatives of different Athlon X2 generations haven’t yet become history. You can clearly see it if you follow the major milestones in the evolution of the AMD Athlon X2 family. The following table lists all specifications of the major processor cores that are compatible with the existing Socket AM2 form-factor:

4 evolution of the amd athlon x2 family

So how did AMD benefit from this multi-stage improvement of their solutions that are, in fact, part of the same exact platform? How much faster will the new Athlon II X2 and Phenom II X2 processors be than the good old 90nm and 65nm cores that have already stood the test of time? Trying to answer these questions we tested all five processor types listed above at the same frequency of 3.0GHz forced for all of them.

5 sysmark performance
6 photoshop performance
7 3ds max spec rendering
8 folding@home performance
9 crysis warhead mq
10 call of duty world at war mq

Progress never stops. AMD has been gradually improving the performance of their processors with each new core (except Brisbane). As a result, the today’s top of this evolutionary chain – Phenom II X2 CPUs – are about 25% faster than the first Athlon X2 for Socket AM2 working at the same clock speed. The biggest performance boost occurred when they switched to K10 (Stars) microarchitecture. However, the new CPUs on 45nm cores do not lose their face either. The new Athlon II X2 can outperform Athlon X2 7000 series processor on Kuma core working at the same clock frequency by almost 7%, while Phenom II X2 increases this advantage by additional 11%.

In other words, the launch of new dual-core processors manufactured with contemporary 45nm process not only allows AMD to increase clock frequencies further up, but also raises the performance bar for mainstream processors due to microarchitectural improvements and larger cache memory.

Phenom II X2 vs. Athlon II X2

Although we clearly understand what reasons stand behind the launch of these two similar dual-core processor families, we are not quite sure that it made sense to launch them both at the same time. We will be able to address our concerns by comparing the performance of the new Phenom II X2 and Athlon II X2 processors working in identical platforms and at identical clock speeds of 3.0GHz.

11 phenom II x2 vs athlon II x2

Overall, Callisto core featuring L3 cache memory performed faster in most benchmarks. And it totally corresponds to the way the manufacturer positions these two new processor families one against the other: Phenom II X2 will cost about 7-10% more than Athlon II X2 working at the same frequency.

Moreover, it is very interesting that L3 cache memory in Phenom II X2 processor provides the most performance benefits in games and office applications. This is exactly where Phenom II X2 500 processors should be primarily used. As for media content processing, rendering and other computational tasks, L3 cache memory doesn’t do that much good there that is why cheaper Athlon II X2 CPUs can offer better price-to-performance ratio for these applications there.

Note that the average advantage Phenom II X2 processor has over its younger brother working at the same clock speed is not very convincing and makes only 5%. And it means that Athlon II X2 with at least 200MHz higher clock frequency will outperform a more expensive Phenom II X2 CPU. Therefore, AMD will have to maintain hierarchy among their new dual-core solutions and make sure that the clock speeds within Athlon II X2 processor family do not grow too fast.


General Performance

12 sysmark performance
13 sysmark 3d performance

SYSmark 2007 benchmark that tests the systems performance during regular everyday type of work makes new AMD CPUs looks very attractive. Athlon II X2 250 outperforms new Intel Pentium E6300 processor, while Phenom II X2 550 competes efficiently against Core 2 Duo E7500. In other words, new AMD processors convincingly outperform more pricy Intel solutions in both cases. And taking into account our recent comparison of Athlon X2 and Pentium processors, we can conclude that the transition to 45nm manufacturing process really helped AMD return to the mainstream dual-core processors market.

However, as you may have noticed new AMD Athlon II X2 and Phenom II X2 processors present a hidden threat to triple-core AMD solutions. Due to their high clock frequency, these dual-core CPUs perform faster than their triple-core Phenom II X3 710 brother that is, in fact, positioned as a higher-end processor and a direct competitor to Intel Core 2 Duo E8000.

If we analyze the results demonstrated by the new solutions in different SYSmark 2007 scenarios we will be able to make a few more interesting conclusions. For example, the performance of our testing participants in Productivity test indicates that the size of processor cache-memory is very important for common office work and sometimes may be of even greater significance than the CPU clock speed. However, during work with video content Athlon II X2 250 without any L3 cache runs even faster than Phenom II X2 550. Another interesting situation occurs in 3D modeling applications. Despite the fact that Intel processors fall behind in all other patterns, they suddenly make a leap forward leaving behind not only new dual-core AMD solutions but also new-generation triple-core Phenom II X3 710 CPU.

Gaming Performance

14 crysis warhead mq
15 far cry 2 mq
16 left 4 dead mq
17 call of duty world at war mq

New dual-core AMD processors performed very well in 3D games. It is especially true for Phenom II X2 550, which L3 cache helped it outperform not only Pentium E6300 and Core 2 Duo E7400, but often also Core 2 Duo E7500. As a result, Phenom II X2 550 may be considered an excellent budget dual-core CPU for gaming. As for Athlon II X2 250, it didn’t do as remarkably in games, as its elder brother. However, nevertheless, it still outperforms its 65nm predecessor, Athlon X2 7850, quite significantly – by 13-17%. Although the new Athlon II X2 250 is still not fast enough to catch up with Core 2 Duo.

Moreover, we have to say that many contemporary games have already learned to use more than two processor cores efficiently enough. That is why triple-core Phenom II X3 710 working at 2.6GHz frequency may often offer better performance than dual-core 3GHz CPUs based on the same microarchitecture.

Audio and Video Encoding

18 divx performance

You will be able to encode mp3 audio in Apple iTunes application if your system is built around an Intel CPU. Nothing helps the new dual-core AMD solutions here: neither larger cache, nor K10 (Stars) microarchitecture. However, when we get to video encoding with DivX or x264 codec that becomes more popular these days, Athlon II X2 and Phenom II X2 processors can boast very good results. In fact, thanks to high clock frequency that has finally reached a competitive level, these new processors can successfully contend for the palm against Core 2 Duo E7000 solutions. By the way, note that media content encoding tasks are pretty indifferent to the cache-memory size and structure. It is the clock frequency that matters the most here.

Other Applications

19 3ds max rendering spec

We have already mentioned several times before that AMD processors do not do final rendering very fast, especially in a popular 3ds max suite. Things haven’t got any better with the launch of the new 45nm AMD solutions. The top CPU announced today, Phenom II X2 550, can only boast reaching the performance level of the budget Intel Pentium E5400 model. As for the Athlon II X2 250, we would prefer not to say anything at all at this point. So, it looks like only triple-core AMD CPUs can actually compete against Core 2 Duo in this type of tasks.

Although Folding@Home is also one of the computational tasks, new dual-core AMD processors do a little better here. Athlon II X2 250 runs as fast as Pentium E5400, while Phenom II X2 550 catches up with Core 2 Duo E7400.

20 microsoft excel performance

Unfortunately, new dual-core AMD CPUs still run very slow during mathematical calculations in Microsoft Excel. Just like in 3ds max, only triple-core Phenom II X3 can be considered a worthy alternative to Intel dual-core choices.

21 photoshop cs4 performance

Things are also not quite rosy in Adobe Photoshop. As you can see from the results charts, new dual-core Phenom II X2 and Athlon II X2 processors not always solve the performance issues for AMD in the mainstream segment. There are quite a few popular applications where AMD solutions still yield significantly to Intel CPUs, which comes from the bottlenecks of the K10 (Stars) microarchitecture. It is especially frustrating that there is no hope for things to get better any time soon.

22 winrar performance

However, new 45nm processors can boast high performance during data compression by archiving tools. The results of WinRAR test are a perfect illustration for that. Even Athlon II X2 250 outperforms Core 2 Duo processors from the E7000 series. Phenom II X2 550 runs another 11% faster that its younger brother.

Power Consumption

Our previous tests showed that AMD solutions manufactured with 65nm process cannot compete against contemporary dual-core Intel processors. It seems that the today’s launch of the new Phenom II X2 and Athlon II X2 processor series could easily turn things around, because these processors use more energy-efficient dies manufactured with more progressive 45nm process. It is especially true for Athlon II X2, which is based on the new Regor core with simpler internal structure. Besides, AMD claims a 65W thermal envelope for this particular processor family – exactly the same as Intel sets for their dual-core processors these days.

Therefore, we were especially curious about the results of our upcoming power consumption tests. The numbers below show the total power consumption of the tested platforms (without the monitor). During our tests we used 64-bit LinX 0.5.8 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.

23 idle power consumption

Despite all AMD’s efforts aimed at lowering the power consumption of their platforms and introduction of Cool’n’Quiet 3.0 technology that uses additional energy-efficient modes for the new 45nm processors, systems built around dual-core Intel CPUs remain a little more energy-efficient.

We see a similar picture under maximum load: Pentium and Core 2 Duo processors consume considerably less power than the new dual-core AMD CPUs. Unfortunately, AMD failed to catch up with Intel in terms of performance-per-watt. However, we have to give them due credit for the obvious tendency towards putting their processors power consumption levels within acceptable ranges. Although the new Phenom II X2 550 is based on an originally quad-core die, it consumes about 20W less than a last-generation dual-core Athlon X2 7850 processor.

24 100 load power consumption

However, we were much more impressed with the power consumption readings taken off the Athlon II X2 250 based platform. The claims of 65W thermal envelope are totally justified. It consumes only 10W more under heavy load than the same system with Intel Core 2 Duo E7500 inside. And it means that we can compare Athlon II X2 250 with Core 2 Duo E8000 series in terms of electrical parameters, which is a significant achievement for AMD.

Nevertheless, we can’t yet claim that AMD managed to create real energy-efficient dual-core solutions that would offer attractive combination of performance and power consumption. However, AMD haven’t yet exhausted their possibilities here. They are going to announce more energy-efficient dual-core processors on Regor core very soon that will boast even lower TDP than the today’s freshly launched Athlon II X2 250. They promise it to be at only 45W!


Another aspect of the new dual-core AMD processors that we couldn’t leave out today is overclocking, of course. The thing is that transition to new 45nm cores stimulated new wave of enthusiasts’ interest to AMD solutions. New Phenom II CPUs started overclocking very well, especially compared with their predecessors. And even though we know that Deneb based processors can go maximum as high as 3.7-3.8GHz with air-cooling methods, we tried to experiment with the Phenom II X2 550 and Athlon II X2 250 processors that we received in our lab. We used a relatively old but reliable Scythe Mugen cooler for our overclocking experiments.

The first one to take the stand was Phenom II X2 550. As we have already mentioned, it belongs to the Black Edition family, so it can be overclocked by simply changing its clock frequency multiplier, which is unlocked by the manufacturer.

Frankly speaking, we didn’t expect this CPU to do too much better than the previously reviewed Phenom II X3 and Phenom II X4 solutions. However, we were very surprised with the obtained results. The thing is that with the Vcore increased by only 0.15V above the nominal (up to 1.475V), we could get it to work stably at 3.98GHz. We checked the system stability in this mode under heavy workload created by LinX Linpack code.

This is a truly unexpected result that contradicts everything we have seen before during our overclocking experiments with AMD processors on Deneb and Heka cores. However, our joy didn’t last long, unfortunately. Our tests showed that even though this system passed heavy processor tests, it was unstable in 3D applications including games.

Therefore, we had to lower the frequency quite a bit. Phenom II X2 550 could stay indisputably stable only at 3.8GHz.

As you can see from the screenshot, we increased the CPU Vcore to 1.475V. The second processor voltage, CPU NB, remained unchanged, because increasing it didn’t allow us to set the frequency of the integrated North Bridge anywhere above 2.0GHz. At 2.2GHz our test CPU started having some issues with the memory subsystem. As a result, Phenom II X2 550 processor ended up acting just like its elder fellows, despite the extremely promising start. No doubt that overclocking results were predetermined by the use of the same semiconductor die as in Phenom II X3 and Phenom II X4 CPUs.

Athlon II X2 250, however, is a different story. This processor is built on a unique semiconductor die that isn’t used in any other CPU models yet. And since it is smaller in size and has lower TDP, we can expect it to do much better during overclocking.

However, we didn’t get any significantly different results when we increased the core voltage by 0.175V (to 1.5V). The CPU worked stably at 3.9GHz, which is as good as it gets.

Note that since Athlon II X2 250 doesn’t belong to the Black Edition family, we had to increase the clock generator frequency to 260MHz to achieve these results. This is where the absence of any L3 cache came in very handy: Athlon II X2 250 didn’t mind speeding up its integrated North Bridge and we didn’t have to lower the corresponding multiplier. As a result, its frequency increased to 2.6GHz, which was no big deal for it as long as we slightly increased its voltage (by 0.1V).

So, Athlon II X2 250 proved to be a little more overclocking-friendly than its elder brother, Phenom II X2 550, even though it is not one of those Black Edition units. Of course, it is way too early to make any final conclusions about the new processors’ overclocking potential judging only by the results obtained on the very first samples. But at this point it looks like Regor core boasts slightly better frequency potential than Deneb and its modifications called Heka and Callisto.

We would like to add the results of a few benchmarks here to complete the picture. The thing is that we were curious to see how the performance levels of overclocked Phenom II X2 550 and Athlon II X2 250 would compare to one another and to overclocked dual-core Intel processors. Therefore, the charts below show the performance results for the following CPUs:

  • AMD Phenom II X2 550 at 3.8GHz frequency = 19 х 200MHz. Memory – DDR3 1600 with 7-7-7-20 timings;
  • AMD Athlon II X2 250 at 3.9GHz frequency = 15 x 260MHz. Memory – DDR3 1386 with 6-6-6-18 timings;
  • Intel Pentium E5400 at 4.0GHz frequency = 12 x 333MHz. Memory – DDR3 1333 with 6-6-6-18 timings;
  • Intel Pentium E7400 at 4.0GHz frequency = 10 x 400MHz. Memory – DDR3 1600 with 7-7-7-20 timings.

Note that 4.0GHz frequency for Intel processors was selected as the most typical result easily achieved with air-cooling solutions.

25 folding@home

The performance tests showed that dual-core Intel processors remain a more attractive choice for an overclocked system. They boast better overclocking potential, higher end frequencies and as a result, higher performance in overclocked platforms even compared with the new 45nm AMD CPUs. However, things are not that dramatic for AMD, because sometimes the performance difference is fairly small. So, we are sure that enthusiasts should not exclude AMD processors from their possible choices, because overclocking is also a lottery in a way.

At the same time it is quite hard to pick the most optimal solution for overclocking needs from the new AMD offerings even after we have checked out the results. Although we managed to push the frequency of Athlon II X2 250 a little higher than that of Phenom II X2 550, it wasn’t always faster. Sometimes the L3 cache of the new Phenom II X2 mattered more than higher clock frequency.

Unlocking Blocked Cores

I don’t think I need to remind you about the most important news of the triple-core Phenom II X3 launch back in the days. Since these processors were based on the same quad-core semiconductor dies as the Phenom II X4 solutions, it turned out possible to unlock the deactivated core and turn this processor into a quad-core one. And the greatest thing about it was no need for any hardware modifications: all you had to do was to check the corresponding BIOS option responsible for Advanced Clock Calibration (ACC) function. Of course, you may not be able to enable the fourth core on some processors, only on those using a fully-functional semiconductor die without any defects. Luckily, the probability of getting a “good” CPU sample was pretty high for the first batches of Phenom II X3 processors and the trick with unlocking the fourth core helped increase the popularity of this AMD solution.

Many enthusiasts are anxious to learn if the same can be done for the new dual-core AMD processors. Let’s find out.

First we would like to remind you that the idea of unlocking blocked cores is only valid for Phenom II X2 CPUs. Its younger brother, Athlon II X2, is based on a dual-core die right from the start and there is nothing to unlock there.

Secondly, the implementation of Advanced Clock Calibration technology in the BIOS of many mainboards has changed, since the launch of Phenom II X3 processors. AMD wasn’t going to watch the enthusiasts raving about their success in unlocking additional cores and tried to force mainboard makers to update their BIOS code with the new versions offering no options for core unblocking. But luckily, not all mainboard makers complied with AMD’s wishes. For example, new BIOS updates for the Gigabyte MA790FXT-UD5P mainboard that we use in our testbed even got an additional option that offers you to choose between two BIOS versions: new one without the option for unlocking blocked processor cores and old one with this option.

26 advanced clock calibration bios

This option is called EC Firmware for Advanced Clock Calibration. You have to set it “Hybrid” and then enable Advanced Clock Calibration in order to be able to activate the processor cores, like you did before. And to our great joy we can assure you that it works not only for Phenom II X3, but also for the new Phenom II X2 processors.

We managed to activate both blocked cores on our Phenom II X2 550 sample and turn it into a fully-functional quad-core CPU without any effort. By the way, it immediately overclocked to 3.8GHz.

27 phenom II x2 550 overclocked

In other words, dual-core Phenom II X2 550 could, in fact, be a high-performance quad-core processor. But it also could not be one, because everything here depends on the semiconductor die used: if it is a fully-functional die with two blocked cores or a die with two defective ones that have been blocked. And considering the fact that AMD is going to price their dual-core processors very democratically, there is really little chance of unlocking the blocked cores successfully. We believe you have more chances of coming across fully-functional Phenom II X2 processor samples only in the first CPU batches. So, if we are seriously hoping to get a “lucky” dual-core, then we would strongly recommend that you do not to put it off for long.

Besides, do not forget that it is not enough to have a “lucky” Phenom II X2 processor. You also need an appropriate mainboard that should be able to enable ACC “the old-fashioned way”. AMD is currently working very hard to ensure that these boards become as few as possible.

By the way, we have to point out that Phenom II X2 with unlocked cores does in fact differ from the real Phenom II X4. Firstly, the mainboard recognizes it as some mysterious Phenom II X4 B50 CPU. And secondly, unlocking blocked cores sets processor thermal diodes out of service, just like in case with unlocking the third core in triple-core processors.


Unfortunately, we can’t yet state that there is anything where AMD is indisputably better than its competitor. But it doesn’t at all mean that the new dual-core processors turned out bad. On the contrary, the new Phenom II X2 and Athlon II X2 look more than revolutionary against the background of their predecessors. While previous dual-core AMD processors could only be positioned against the youngest budget Intel Pentium CPUs and not without numerous allowances, now we have every right to say that AMD is offering competitive dual-core choices closing the gap in the $80-$100 price range.

Phenom II X2 processors that made us say “wow!” more than once during this test session look especially attractive. Their major advantages include high (for their price point) performance in games, office applications and video encoding tasks, as well as a chance of enabling two additional cores. These qualities make Phenom II X2 extremely attractive even despite pretty high power consumption for dual-core CPUs and not the best overclocking scores. In other words, thanks to the new Phenom II X2 processors AMD has real opportunity to take some market share away from the competing Core 2 Duo solutions.

However, we are a little concerned with the availability of these processors. Since they are based on the quad-core semiconductor Deneb dies, their production is not too rewarding for AMD. Therefore, they will most likely be made from what cannot be used for quad- and triple-core processors. And it in its turn means that Phenom II X2 production volumes will be directly connected to the 45nm process yields and production volumes of higher-end processors rather than consumer demand. This is exactly why the market should be ready to experience certain shortage of the new Phenom II X2 processors followed by inevitable price increase.

It is a different processor family that is destined to become a true mass dual-core solution – Athlon II X2. It certainly has a few drawbacks compared with Phenom II X2. These processors are based on their own semiconductor die called Regor that has no L3 cache. As a result, Athlon II X2 runs slower in a number of applications. In fact, we can even state that these processors can only compete successfully against top Pentium solutions, but not against junior Core 2 Duo models. Besides, Athlon II X2 has no hidden bonuses for us, like the opportunity to unlock any additional cores.

However, the new Athlon II X2 family is still a tremendous improvement compared with the previous generation Athlon X2 processors. The new CPUs boast very good overclocking potential, consume a lot less power and, of course, run faster. Moreover, AMD will definitely not stop here and Athlon II X2 family should very soon expand not only towards higher clock speeds but also towards lower levels of heat dissipation and power consumption.

And of course, how could we deny the fact that AMD’s pricing strategy used for promotion of the new 45nm Phenom II X2 and Athlon II X2 processors, as well as all other CPU models, is extremely attractive from the consumer standpoint. It is based on a very simple rule: any Phenom II and Athlon II processor models offer higher average performance than the solutions from Intel with the same price tag.

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XbitLabs Team

We are a team of enthusiasts thriving to provide you with helpful advice on buying tech.

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9 months ago

Last update 29 Apr 2021, why was this updated.