by Ilya Gavrichenkov
04/13/2006 | 04:26 PM
Beside everything else, the beginning of this year was marked with yet another breakthrough in the mobile computing market. In January 2006 Intel announced a new hardware platform for notebooks and christened it Centrino Duo (it had been previously known under the codename of Napa). The most exciting thing about the new platform is that it includes a dual-core mobile processor Core Duo (Yonah) which is the first such solution to come to the mobile market.
The multiple-core tendency in modern CPU development at last found its way into notebooks. This is not something unexpected, though. According to Intel’s plans, and this company is not only a trend-setter in this field but also the leader in terms of sales volumes, dual-core processors will be installed in about 70% of all shipped notebooks by the end of this year.
It should be noted that Intel has managed to outpace AMD and release its dual-core mobile processor before the competitor (AMD’s dual-core Turion 64 X2 is expected to be announced only in June). It is rather unusual since Intel hasn’t been the first to introduce new architectures or technologies in server or desktop processors for the last couple of years. But it is a fact that Intel’s engineers successfully developed and put into production a new dual-core mobile processor based on the existing Pentium M architecture and they have done so ahead of the competitor who’s going to adapt its ordinary dual-core Athlon X2 for use in notebooks.
We’ve already had many opportunities to see the advantages of dual-core processors over single-core models. Today most software is optimized for multi-threaded environments, so processors with two physical cores can lift the performance of the computer quite high. Moreover, dual-core processors can improve the user’s experience even with non-optimized software because the OS takes less time to switch between applications or several resource-consuming applications may be running very effectively in parallel.
In this review we are going to have a closer look at the new Centrino Duo platform and examine each of its components: the dual-core processor, updated chipset, and improved wireless network adapter.
The goal of this article is to show you the advantages that users of mobile computers on the new hardware platform from Intel may expect to have. So besides a purely theoretical part, we’ll also offer you the results of a comparative test of real-life products on the older Centrino and on the new Centrino Duo platform.
It is the innovative Core Duo processor that is the keystone of the new mobile platform. It is based on a well-known architecture borrowed from the Dothan-core Pentium M that used to come as part of the last-generation Centrino platform throughout the entire last year. Easy to guess, the main feature of Core Duo CPUs is that the new mobile processor from Intel incorporates two execution cores, architecturally alike to the Dothan. Unlike dual-core processors for desktop PCs, the Core Duo is surely the most densely integrated processor in its class. Its cores not only reside on a single semiconductor die, but also use a single and common L2 cache. This is a significant difference from Intel’s modern Pentium D for desktop computers which is based on the Presler core. Today’s desktop CPUs from Intel not only have a separate L2 cache for each core, but physically consist of two semiconductor dies that communicate via the printed-circuit board the cores are mounted on.
Well, it’s not quite correct to draw parallels between Intel’s mobile and desktop processors. It’s not a secret that these CPU families use different architectures since early 2003: the Pentium 4 and Pentium D are based on the NetBurst architecture whereas the mobile Pentium M and its modern successor Core Duo trace their origin back to the good old Pentium III. The Pentium III architecture just proved to have a better performance-per-watt ratio which is very important not only for a notebook’s performance, but also for the battery life.
It’s not that the Core Duo is just a dual-core Pentium III, though. The architecture was improved in many ways as it was transferred into the mobile CPU family, and these improvements are all available in the Core Duo, too. Main improvements in comparison with the Pentium III are: a longer execution pipeline, improved branch prediction mechanism, micro-ops fusion, dedicated stack manager, Quad Pumped Bus, SSE2 instructions set, and special technologies for lower power consumption and heat dissipation. You can learn more about the Pentium M architecture from our artcile called Intel Pentium M 780 as Heart of Your Desktop PC, with ASUS CT-479 Adapter. Intel’s engineers also made use of the transition from the single-core Pentium M to the dual-core Core Duo to add some more improvements into the micro-architecture.
The most important of them is the so-called Intel Digital Media Burst technology. It actually means that besides SSE and SSE2 the new Core Duo supports the latest SIMD instructions set, SSE3. SSE3 came to desktop processors quite a long time ago. It first appeared in the Prescott core and CPUs with this core has been selling since early 2004. So it’s quite natural that the 13 SSE3 instructions are now quite frequently employed in various multimedia applications, for example in video codecs, as well as in today’s 3D games.
Maybe not that significant, the other changes in the execution cores of the Core Duo processor should be mentioned, too. Particularly, Intel tried to improve the processor’s FPU which had been rather weak even in the Pentium III. It hadn’t been changed in the single-core Pentium M, so Intel’s mobile CPUs couldn’t boast high performance at floating-point calculations up till now. The Core Duo’s GPU has become somewhat faster at a number of operations, yet we can’t say it is a big step forward. FPU-intensive applications are still relatively slow on systems with the new Core Duo, but you should keep it in mind that such applications – video encoding, 3D rendering, 3D games – are not very often run on notebooks.
The mentioned micro-architectural differences between the Core Duo and the Dothan-core Pentium M are not too significant. The former may even be viewed as an improved version of the latter, but the main advantages of the new CPU come from its dual-core design, of course. And this is rather a non-typical design for today as the two cores share a single 2MB L2 cache. By the way, this is called Intel Smart Cache , and it is smart because the same L2 cache space is intellectually used by both the execution cores.
But what’s good about this design? First, the cache space used by a core can be flexibly adjusted. In other words, each core of the Core Duo processor can access all the 2 megabytes of L2 cache memory. When one core is idle, the other enjoys everything.
If both the cores are at work, the cache space is divided between them depending on how frequently the cores are addressing the system memory. Moreover, if both the cores are processing the same data at the same moment, only one copy of the data is stored in the shared L2 cache. Thus, the smart 1MB L2 cache of the Core Duo processor is more efficient and, so to say, more capacious than two separate 1MB caches as in dual-core processors of Intel’s Pentium D 8XX and AMD’s Athlon 64 X2 families for desktop PCs.
Another important feature of the shared L2 cache is that it helps reduce the load on the system memory and on the processor bus. The system just doesn’t have to control and ensure cache memory coherency. In dual-core designs with separate caches, there are two copies of the same data in each cache when both the cores need them and it is necessary to control if the data hasn’t become out-dated. Before extracting such data from the L2 cache, the processor core must check if the other core hasn’t changed it. If it is so, the cache memory contents must be updated – via the system memory and the system bus. The shared cache design helps abandon such an inefficient algorithm altogether. Moreover, the control logic in the Core Duo allows for direct data transfers between the L1 caches of the cores for more efficient communication when the cores are both working on the same task.
Of course, no improvement ever comes easily. Here, the processor die had to be made larger to unload the CPU bus and solve the coherency problem: the Smart Cache arbiter in the Core Duo die is about one third the size of a single execution core. You can note it’s not easy to manage a shared cache. Using a sophisticated operation algorithm, the cache has also become slower, with a 40% higher latency. The L2 cache latency of the Pentium M on the Dothan core is 10 cycles, while the same latency for the Core Duo is 14 cycles. Intel tried to make up for that by improving the data pre-fetch mechanism for L2 cache, so there’s little difference between the Pentium M and Core Duo on single-threaded applications under the same conditions.
Well, performance is not the single important characteristic of a mobile processor – users are interested in low power consumption, too. When developing the Core Duo, Intel tried its best to make it at least no worse than the Dothan-core Pentium M as concerns power-related characteristics. The dual-core architecture by itself opens numerous power-saving opportunities and the developers were eager to catch at them. New in the Core Duo, Intel Dynamic Power Coordination technology allows to adjust the power-saving parameters of the execution cores independently. So when multi-threaded processing is not necessary at the moment, one execution core can be turned off to reduce the heat consumption and heat dissipation of the whole processor. With Dynamic Power Coordination, a processor core can be switched into reduced power consumption states: Halt, Stop and Deep Sleep. The processor also features two even more economical states for idle modes – Deeper Sleep and Enhanced Deeper Sleep – but they can only be activated for both the cores at once.
Surely the new dual-core processor supports Enhanced Intel SpeedStep technology (EIST) that we’ve got used to see in any CPU from Intel. The technology allows adjusting the CPU clock rate and voltage “on the fly” depending on the current load, but it affects both the cores at once, too. The minimum frequency the Core Duo can work at with enabled EIST is 1GHz irrespective of the default clock rate of the particular CPU model.
The Core Duo’s pack of power-saving technologies is quite efficient as is illustrated by the fact that the maximum power dissipation of the new processor is 31W which is only 4W higher than that of the Dothan-core Pentium M. But the Core Duo has two execution cores rather than one! The average power consumption of the new processor under normal conditions, i.e. at everyday work, is roughly the same as of the single-core predecessor. It means your notebook with a Core Duo inside is going to work nearly as long on its battery as an analogous notebook with a Dothan-core Pentium M.
These facts are impressive and even hard to believe in until you learn of one more technology that complements Smart Cache and Dynamic Power Coordination. This technology allows to adjust dynamically the size of an active portion of L2 cache memory, turning off unused sections. This makes sense considering that the L2 cache accounts for about 35-40% of the total area of the Core Duo chip. It works like this: when the Smart Cache logic finds that some section of the cache memory hasn’t been accessed for a specified period of time, the data from this section are sent to the system memory and the section itself is powered off. By the way, it is this algorithm that makes possible the additional power-saving state Enhanced Deeper Sleep available with the Core Duo. The min voltage level in the Deeper Sleep mode depended on the necessity to keep up the cache memory, but now this is not necessary since data from the L2 cache is transferred into the system memory and the cache itself is turned off when the CPU is idle.
Talking about power consumption, we should also mention the fact that Intel’s engineers have improved the hardware monitoring system that controls the speed of the notebook’s fans. Core Duo processors are equipped with two integrated digital temperature sensors placed in the hottest spot of each execution core. Precise control over the CPU thermal conditions is thus possible and this should ultimately lead to quieter cooling systems (if the notebook manufacturers take the right approach to developing them, of course). There is also a third, common sensor in the Core Duo which is left for compatibility with older hardware monitoring systems.
This is where the architectural difference between the Core Duo and the Dothan-core Pentium M ends. We should only add that the new mobile processor supports Intel Virtualization Technology , but it is unlikely to be used in mobile computers. It must have been implemented in the Core Duo because Intel is going to promote this processor as a possible foundation for the entertainment platform Viiv.
You may have noticed that we’ve never mentioned Enhanced Memory 64 Technology (EM64T – 64-bit extensions to the x86 architecture) in this article so far. Unfortunately, the new Core Duo, like its predecessor Pentium M, is a 32-bit processor. Well, you should realize that the Pentium III, the forefather of all modern notebook-oriented CPUs from Intel, came to market back in 1999 and had nothing to do with 64-bit software applications. It would have taken a thorough overhaul of the micro-architecture to implement x86-64 support in the Core Duo, and Intel wasn’t ready for that. But Intel is already working on a next generation of mobile processors currently known under the codename of Merom. This true 64-bit CPU is expected to arrive to market in October-November this year and will make a cause for an update of the Centrino Duo platform.
Physically the Intel Core Duo chip has a 479-pin packaging, but is not compatible with Socket 479 mainboards. We aren’t surprised at that at all as Intel has made a point of changing its CPU sockets regularly.
Yonah (left) and Dothan (right) processors
The new processor’s pin values are different from those of the Pentium M. The pins of the Core Duo are also placed in a different way. This raises a physical barrier against upgrading an old mobile computer with the new dual-core processor. Moreover, the new CPU uses a faster Quad Pumped Bus (667MHz instead of 533MHz), which is quite reasonable considering the doubled number of execution cores. Unfortunately, this is still much below the peak theoretical bandwidth of dual-channel DDR2-667 SDRAM employed in modern notebooks – 10.7GB/s.
Like the modern dual-core processors fro desktop computers, Core Duo processors are manufactured on the new 65nm P1264 tech process. Intel has managed to transition to the more advanced manufacturing technology sooner than the competitor; AMD is only going to transition to 65nm at the end of this year at best. Thanks to the new tech process, the 151.6 million transistors of the Core Duo processor occupy an area of only 90.3 sq. mm. The dual-core chip is a mere 8% larger than a Pentium M on a single 90nm Dothan core, which means its production cost isn’t going to be high (if the tech process runs smoothly).
Yonah (left) and Dothan (right) processors
The following table lists the formal specifications of Intel’s and AMD’s processors for notebooks:
Intel’s Core Duo series includes four models with clock rates ranging from 1.66 to 2.16GHz. A speedier, 2.33GHz model will be added in the second half of the year. There also exist two economical Core Duo models clocked at 1.5 and 1.66GHz. Looking somewhat oddly among dual-core solutions, the 1.66GHz Core Solo processor also belongs to this series. Despite the different name, this processor is a regular Yonah, but with one disabled core. Do not mistake the Core Solo for an analog of the Celeron. The Solo is not a value processor; it is just targeted at applications that do not require multi-threading, but it retains all the strong points of the Core Duo architecture. We don’t think the Core Solo will be very popular because Intel currently compensates the disabled core with a too small price reduction, by 15%.
And finally the CPU rating system Intel uses for its Core Duo processors should be described. Instead of a 3-digit number typical of Pentium 4, Pentium M and Pentium D, the new series of mobile processors employs a new marking system.
The new Core Duo and Core Solo mobile processors are marked with an index consisting of one letter and four digits. Strange though it seems, the new indexing system resembles the rating system of AMD’s mobile processor Turion 64. In the name of a Core Duo or Core Solo processor, the letter denotes a power consumption class (Intel mentions three possible variants so far: U stands for Ultra Low Voltage, L for Low Voltage, and T means an ordinary processor), and the 3-digit combination indicates the processor’s performance level within its class.
The new Centrino Duo platform includes a new chipset, too. It’s not surprising since Core Duo processors use a 667MHz system bus that is not supported by Intel’s last-generation i915PM/GM chipsets. The new chipset for the Core Duo processor is called i945PM/GM (Calistoga) which resembles the name of a similar product for desktop computers. Well, the new mobile chipsets are really developed out of their desktop analogs with power-saving options in mind. The i945PM/GM can control their own power consumption as well as optimize the consumption of the memory modules installed in the system.
The i945PM/GM do not differ much from Intel’s earlier mobile chipsets (i915PM/GM), at least, there is nothing completely new in them. They have just improved over the older ones in some characteristics. The improvements are not to be underestimated, though.
Besides the faster Quad Pumped Bus (which works now at 667MHz and yields a bandwidth of 5.3GB/s), the i945PM/GM chipsets support faster DDR2 SO-DIMMs. The earlier mobile chipsets could only work with dual-channel DDR2-533 SDRAM, but the new ones support dual-channel DDR2-667 SDRAM. It means the memory subsystem bandwidth has increased to 10.7GB/s, which should have a positive effect on the performance of mobile computers.
The Intel 945 mobile chipset family consists of two products: an i945GM with an integrated graphics core and a discrete i945PM. The increased memory bandwidth we’ve talked about above may improve the performance of systems that use some of the system RAM for the purposes of the graphics subsystem. We mean i945GM-based platforms in the first place.
The graphics core in the i945GM is somewhat different from the one in the last-generation i915GM chipset and is indicated by the different name, Intel Graphics Media Accelerator 950 (the older was called GMA 900). You shouldn’t look for any dramatic changes in the new graphics core, though. Its architecture has remained the same. GMA 950 has 4 pixel pipelines and is capable of mapping up to 4 textures per clock cycle. Like GMA 900, it provides hardware support for Pixel Shader 2.0 and software support for Vertex Shader 3.0 and T&L. GMA 950, and GMA 900 too, is a fully DirectX 9 compatible graphics accelerator.
You may wondering what is the difference between the new and older graphics cores, but the answer is simple – frequency. Besides the higher system memory frequency (which is also used as graphics memory), the graphics core frequency has been raised, too. The GMA 900 core worked at 333MHz at the maximum (the frequency could be lowered to save power), while GMA 950 can be clocked at 400MHz.
Like the i945PM, the i945GM is equipped with a PCI Express x16 bus for connecting an external graphics card – the new chipsets do not differ from their predecessors in this respect. The i945PM/GM use an ICH7-M chip as a South Bridge; it is connected to the North Bridge via a special-purpose Direct Media Interface (DMI) with a peak bandwidth of 2GB/s.
The South Bridge in the i945PM/GM chipsets supports one Parallel ATA and two Serial ATA ports, eight USB 2.0 ports and integrated High-Definition Audio. It also supports six PCI Express x1 lanes for peripheral devices like a Gigabit Ethernet controller or Wi-Fi adapter.
To finish this section of the article we offer you a table in which the i945PM/GM chipsets are compared with the chipsets from the last-generation Centrino platform:
Mobile Intel 945GM/PM
Mobile Intel 915GM/PM
Intel Core Duo,
Intel Pentium M,
Maximum memory size
Up to 4GB (at 533MHz)
Up to 2GB
Supported memory types
Integrated graphics core (for i9X5GM)
Intel GMA 950
Intel GMA 900
PCI Express x16
PCI Express x16
Integrated TV Out
Maximum supported resolution
IDE / ATA
ATA-100 (1 channel),
ATA-100 (1 channel),
8 USB 2.0 ports
8 USB 2.0 ports
Integrated LAN MAC (10/100 Ethernet)
PCI Express x1 slots
Intel High Definition Audio 24bit 192KHz, AC'97 2.3
Intel High Definition Audio 24bit 192KHz, AC'97 2.3
82801GBM / 82801GHM
Bus between bridges
Direct Media Interface 4x
Direct Media Interface 4x/2x
I would like to remind you that the mobile Centrino platform, as well as its new reincarnation aka Centrino Duo, includes not just the CPU and the chipset, but also a WiFi controller. Therefore, Intel paid special attention to upgrading this component, too. The wireless network adapter bundled with the Core Duo and Core Solo platforms – Intel PRO/Wireless 3945ABG (Golan) – differs from its predecessors by the connection to the chipset South Bridge via the PCI Express x1 bus. As a result, it takes a lot less space inside the notebook. Moreover, according to the details reported by the manufacturer, the new WiFi component is more immune to interferences, and imposes less interference over other devices, such as Bluetooth in the first place.
I have to stress that in terms of supported features Intel PRO/Wireless 3945ABG component is not very much different from its PCI counterparts that have been used in Centrino platforms before. However, I would like to say that Intel has also accompanied its new WiFi adapter with the updated modified software that features slightly different interface and is specifically optimized for IP-phone environment.
Other than that the features of Intel PRO/Wireless 3945ABG are quite common: it supports IEEE-802.11 a, b and g and WPA/WPA2 encoding algorithms.
There are a lot of notebooks based on the new Intel mobile Centrino Duo platform these days. However, the previous Centrino platform including the Intel Pentium M processor and i915PM/GM chipsets doesn’t feel like giving up its positions either. Therefore, we decided to perform a comparative testing of two notebooks based on two different mobile platforms from Intel.
For our test session we picked two notebook computers from the same category and similar price range based on the old Centrino and the new Centrino Duo platforms. The notebooks we selected for our experiment come from ASUS: U5A and W5F. Both notebooks feature s 12.1-inch screen and can be considered highly mobile devices thanks to their relatively small weight: 1.4-1.6kg. ASUS U5A notebook is built around i915GM chipset and Pentium M 760 processor working at 2.0GHz frequency. ASUS W5F notebook is based on i945GM chipset and Core Duo T4200 processor working at 1.83GHz frequency. Both mobile platforms participating in our test session were equipped with 1GB of dual-channel DDR2-533 SDRAM working at 4-4-4-12 timing settings.
Below you can see the screenshots from the CPU-Z diagnostic utility taken on both notebooks during our test session.
These platforms are based on integrated mobile chipsets, which implies that ASUS U5A notebook features Intel GMA900 graphics core, and ASUS W5F notebook – Intel GMA950 graphics core. And we have every right to consider these two ASUS notebooks great representatives of the common Centrino and Centrino Duo platforms because they are both equipped with default WiFi components: Intel PRO/Wireless 2915ABG and Intel PRO/Wireless 3945ABG respectively.
It is important to note that both mobile computers participating in our test session were equipped with the same capacity batteries: 4800mAh.
As usual, we checked the performance of our systems in general-purpose applications with the help of SYSMark2004 SE test. This benchmark emulates the user’s work in popular applications involving a lot of multi-tasking. Before we pass over to the results, we would like to stress that SYSMark2004 SE is primarily positioned as a desktop testing suite. Therefore, it includes a lot of applications that can be far from typical for a mobile system. That is why we believe it makes more sense to provide the detailed results report focusing specifically on each type of the workload.
In this case we have an image rendered by 3ds max 5.1 into a bmp-file, while the user is preparing web-pages in Dreamweaver MX. Then the user renders some 3D animation into vector graphics format.
Since this work model uses a lot of heavy applications supporting multi-threading, the obtained results were quite expected. Dual-core Core Due processor makes the notebook run undoubtedly faster.
Now the test is emulating the user’s work in Premiere 6.5, when he is creating a video movie in raw-format from a few other movies and separate sound tracks. While waiting for the operation to be completed, the user is also modifying and saving to the hard drive a picture in Photoshop 7.01. When the video is finished, the user does the necessary editing and adds special effects to it in After Effects 5.5.
All three Adobe applications used in this test are optimized for multi-threading. We have already seen it many times. So, the obtained results are quite logical. Dual-core processor architecture once again proves how efficient it is.
Here, our hypothetical user extracts from the zip-archive the web-site content and at the same time opens an exported 3D vector video in Flash MX. Then the user modifies it by adding some new pictures and optimizes it for faster animation. The final video with applied special effects is then compressed with Windows Media Encoder 9 so that it could later be broadcast via internet. The created web-site is then composed in Dreamweaver MX, while the system is scanned for viruses with VirusScan 7.0.
Once again we can see that the notebook based on single-core Pentium M processor gave in to the faster leader. The reasons are the same: the software is optimized for multi-threaded environment and besides there are several tasks performed at the same time, which is exactly what the dual-core processors are best at.
In this case the scenario is quite typical of the average notebook user. Here the test is emulating the user’s work when he is receiving an e-mail in Outlook 2002 with a number of documents in a zip-file attached to it. While the files are being scanned for viruses with the VirusScan 7.0, the user is looking through the e-mails and makes notes in the Outlook calendar. After that the user checks a corporate web-site and some documents through Internet Explorer 6.0.
There are not that many parallel tasks here, so the notebooks built with Pentium M 760 and Core Duo T2400 processors perform almost equally fast. Although dual-core architecture still manages to show its bright side: if you remember the CPUs we compare work at different clock speeds of 2.0GHz and 1.83GHz respectively.
In this test the hypothetical user is editing some test in Word 2002 and uses Dragon NaturallySpeaking 6 to convert an audio file into a text document. The document is then converted into pdf-format in Acrobat 5.0.5. After that the prepared document is used to create a PowerPoint 2002 presentation.
Core Duo processor once again demonstrates its high potential in real tasks. Despite its lower clock frequency, it finishes the above described scenario faster than the single-core mobile Pentium M processor.
In the next test we see the following situation: the user opens a database in Access 2002 and creates a number of requests. The documents are archived with WinZip 8.1. The request results are exported into Excel 2002 and a diagram is created.
The results we see on this diagram can hardly surprise anyone now. Of course a CPU with two computational cores speeds up the user’s multi-tasking work in Windows XP operating system.
Besides SYSMark2004 SE that uses mostly desktop working scenarios, we have also resorted to a special MobileMark2005 benchmarking suite to measure the performance of our Centrino Duo platform. This benchmark works with a user model more typical of mobile conditions. In this case there are the following applications used: Microsoft Word 2002, Microsoft Excel 2002, Microsoft PowerPoint 2002, Microsoft Outlook 2002, Netscape Communicator 6.01, WinZip Computing WinZip 8.0, McAfee VirusScan 5.13, Adobe Photoshop 6.0.1 and Macromedia Flash 5. The benchmark emulates the work model of a car dealership employee who creates and edits documents in Microsoft Word, Excel and PowerPoint, works with an e-mail client, and uses Photoshop and Flash to edit images and animated files for his presentation. He also actively uses the Internet browser and a few additional tools such as archiving utility and antivirus software running in the background.
I would like to specifically stress the fact that MobileMark2005 test is put together in such a way that it measures the performance when the notebook is running on battery. In fact this is not surprising at all: this work mode is much more typical of the notebooks that we are looking at today. Note that during this test session all power saving technologies available in the given platform are activated. Therefore, the numbers given below also take into account the negative effect of Enhanced Intel SpeedStep and Intel Dynamic Power Coordination that slow down the system performance.
The funny thing is that the diagram shows a completely different picture compared with what we have already seen in SYSMark2004 SE. However, this shouldn’t be puzzling for you: there is a logical explanation to any phenomenon. On the one hand, the tested Centrino Duo platform is equipped with a slower processor (from the clock frequency standpoint) than the Centrino platform. On the other hand, the typical notebook usage scenarios (when the notebooks are not used as desktop replacements) are very rarely using heavy applications with multi-threading optimizations and do not really take advantage of operating system multi-tasking. Moreover, MobileMark2005 models the work in relatively old versions of popular applications that have been mostly developed without taking into account the things contemporary processors are capable of.
PCMark05 is another popular testing suite that explores the general system performance. Since it creates multi-threaded workload during work, dual-core processors are usually faster there, than single-core ones.
Besides the CPU test, this benchmark can also check the memory subsystem performance.
However, since both notebooks in our today’s test session are equipped with pretty similar memory subsystems (dual-channel DDR2-533 SDRAM with the same timings set to 4-4-4-12), the results are quite similar as well. Nevertheless, the i945GM based notebook works slightly faster with the memory thanks to its more advanced memory controller that no longer supports the outdated DDR-I SDRAM.
PCMark05 test also allows the Intel GMA950 graphics core to show its best. According to the results obtained in 2D and 3D modes during video playback and during pixel and vertex shaders processing, the new graphics core integrated into the i945GM chipset is more than 20% faster than the previous Intel GMA900 core.
However, they usually use 3DMark testing suites to measure the graphics core performance in 3D mode. That is why we have also run 3DMark05 to verify the results of the PCMark05 test.
According to 3DMark05 that uses all the latest features of contemporary graphics accelerators, Intel GMA950 in ASUS W5F notebook is twice as fast as Intel GMA900 in ASUS U5A notebook. It owes this significant performance advantage not only to higher clock frequency of the Intel GMA950 graphics core, but also to the higher computational power of the dual-core Core Duo processor that is responsible for vertex shaders and T&L calculations.
3DMark05 benchmark also contains a CPU test that uses multi-threading.
The result is quite logical. It once again illustrates that two cores is better that one. At least when the applications are optimized respectively.
Mobile computers with the graphics core integrated into the chipset will hardly ever be used for gaming. However, we still decided to test our notebooks in Quake III and Doom 3, because the benchmarks from these gaming applications are fairly often used to estimate the platforms performance.
Although these old games do not use multi-threading, Centrino Duo platform demonstrated higher results. It owes this victory to faster integrated graphics core, of course.
We picked out a few applications that are most likely to be used on mobile platforms.
First of all we tested how fast our notebooks would be in a popular WinRAR archiving tool:
WinRAR doesn’t support multi-threading, however the performance in this application depends a lot on the memory subsystem. Since i945GM chipset ensures lower memory latency than its competitor, i915GM, Centrino Duo platform runs faster. Even lower clock frequency of the Core Duo processor doesn’t spoil the impression left by this platform.
Then, we paid special attention to audio-files encoding into the popular mp3 format.
Apple iTunes supports dual-core processors and allows using both computational cores efficiently during the encoding process. Therefore, the notebook based on Core Duo processor managed to leave its competitor far behind.
Besides the audio encoding speed, we have also looked at the video encoding.
Contemporary video codecs are optimized for multi-core processors. Therefore, the dual-core Core Duo speeds us ASUS W5F notebook based on Centrino Duo platform.
We have also tested how fast the images can be processed using popular Adobe Photoshop CS2 graphics editor.
The obtained results are absolutely logical: since most Photoshop filters are optimized for multi-threading, the notebook with a dual-core Intel Core Duo processor is much faster than the system with a single-core Pentium M.
Battery life is not any less important feature for a notebook than its performance. That is why we decided to specifically dwell on this characteristic under different types of workload. We tested the battery life with the help of Mobilemark2005 testing suite.
The first scenario emulated the regular user work in typical office applications. Just as during our performance tests, the hypothetical user ran the following applications on the notebook: Microsoft Word 2002, Microsoft Excel 2002, Microsoft PowerPoint 2002, Microsoft Outlook 2002, Netscape Communicator 6.01, WinZip Computing WinZip 8.0, McAfee VirusScan 5.13, Adobe Photoshop 6.0.1 and Macromedia Flash 5. The script used in this case emulated the routine work of a car dealership employee.
As we see, the mobile computer with an older single-core Pentium M processor can guarantee longer battery life. However, the time difference between Centrino and Centrino Duo platforms is only 5%, which is not that bad. Taking into account the performance increase provided by the new platform, the 5% difference seems really insignificant.
The second scenario that we used during our battery life test session emulated the usage model when the notebook is used for video playback. In particular, this test shows how long the notebook battery will last during DVD-movie playback via the InterVideo WinDVD 6.0 player.
In this case both mobile systems demonstrated practically the same results: their batteries lasted about the same. However, regular DVD playback doesn’t really take advantage of the Intel Core Duo specifics, so one of the two cores is mostly in Deep Sleep state all the time.
The third experiment we conducted measured the battery life during text reading. The text was displayed in NetScape Navigator 6.01.
In this case the previous generation Centrino notebook managed to stay on 17 minutes longer. So, book lovers will hardly benefit from the new technologies, according to this test.
The last fourth scenario was aimed at measuring the battery life when the user is browsing internet. The usage model in this case is very simple: the internet surfing is performed in Microsoft Internet Explorer. The notebooks are connected to the internet via the built-in wireless network controllers.
The new Centrino Duo platform performed quite average here. The battery of ASUS U5A notebook with the Pentium M processor lasts about 20% longer, and this is quite a difference I should say.
I would like to say a few words about the lowering of the Centrino Duo battery life one any USB 2.0 devices are connected. According to some news sites, platforms like that may eat up the power resources inappropriately, thus provoking faster battery discharge. The problem allegedly reveals itself if there are any external USB 2.0 devices connected to the notebook. The sources claimed that in this case the battery life night become up to one hour shorter than the time claimed by the manufacturer.
Of course, we couldn’t help checking this out. Luckily, we didn’t find anything like that. The retail ASUS W5F notebook based on Centrino Duo platform that took part in our test session didn’t lose that much of its precious battery life when we connected external USB 2.0 flash drives to it. With all the usage models we tested, the battery life variations stayed within 10% delta margin, which can result from the use of external USB 2.0 devices like flash drives.
Let’s sum up our results. At first glance, the Israeli Intel developer team deserves all the laurels for what they’ve created. Thanks to them, Intel managed to roll out dual-core mobile processing into the market I the right time and even ahead of the competitor. Since the number of applications that can benefit from dual-core processor architecture keeps growing, we cannot underestimate the importance of Centrino Duo platform. The new dual-core Core Duo processor used in this platform can increase the performance of contemporary mobile computers quite tangibly. Besides, it can also improve the user experience thanks to shorter system response time when switching between different tasks.
It is important to stress that the performance improvement isn’t accompanied by such unpleasant factors as the growth of CPU heat dissipation and power consumption. The battery life of Centrino Duo based notebooks is usually as long as that of their predecessors based on the Pentium M CPUs. Intel engineers managed to achieve this thanks to timely introduction of finer 64nm manufacturing process as well as thanks to a new set of power saving technologies and algorithms.
It is especially pleasing that the progress in the mobile segment didn’t cause any growth of the notebook prices. Intel Core Duo processors and Centrino Duo platform are currently selling at the same price rate as the previous generation CPUs and platforms did.
However, there is still one frustrating factor that spoils a little bit this rosy picture. Unfortunately, Intel Core Duo processors have very limited life cycle (and as a result popularity cycle). In the coming fall they will no longer be the latest and greatest mobile processors any more. New dual-core mobiles solutions that are currently known as Merom will be coming out by then. And this fast generations switch has its reasons. The thing is that today’s Core Duo processors have one serious drawback: they do not support 64-bit EM64T extensions. Therefore, when the new Microsoft Vista operating system comes out next year, all today’s advantages of Core Duo can fade away. Although Vista will support 32-bit as well as 64-bit processors, its will be optimized for more advanced CPUs, of course. So, Core Duo processor owners may be quite disappointed in the long run.
Summing up everything we have just said, we can conclude the following. If you need a new notebook, then you have to take a look at the new Centrino Duo platform. It is a good choice as of today, although it is not going to be a good long-term choice. However, if you already have a previous generation Centrino notebook, it doesn’t make much sense for you to upgrade to a new Centrino Duo today. It would be best to wait until fall and get a notebook with the dual-core processor supporting 64-bit extensions of the x86 architecture.
Moreover, we expect dual-core 64-bit AMD processors for the mobile segment to come out in the middle of this year, and they have every reason to turn into a very attractive alternative to Intel’s processors. So, your patient waiting will definitely be rewarded one way or another.