AMD Athlon XP Processor Family Review

by FastSite
11/07/2001 | 12:00 AM

The second half of this year turned out very rich in events for the processor market. Within this period of time, two major players, Intel and AMD, announced several new processor cores, which are now used in the today's CPUs. Intel introduced a new 0.13micron Tualatin core with Pentium III architecture into its value Celeron family, server Pentium III-S family and mobile Pentium III-M family. AMD in its turn moved to a new 0.18micron Palomino core, which is now used not only in server Athlon MP and mobile Athlon 4 CPUs, but also in the desktop Athlon XP family. Besides, AMD bore one more core, Morgan, which is now used in the value Duron processor family. In fact we have already discussed in great detail nearly all the new cores. For more information on them, please check the following reviews:

• Intel Celeron (Tualatin) 1.2GHz Review
• AMD Duron (Morgan) 1.0GHz and 1.1GHz Review
• Dual-Processor Socket A Systems on AMD 760MP Chipset
• Pentium III-S 1.13GHz (Tualatin) Review

The only processor family, which we haven't yet touched upon in our testlab is AMD Athlon XP built on the new Palomino core. Now we are ready to make up for this lack.

Athlon XP is a new processor family from AMD aimed at desktop PCs, which should some day replace the so dear Athlon CPUs. New Athlon XP processors are expected to oust from the market the older Athlon CPUs on Thunderbird core by the middle of next year already. Note that the "XP" letters in the processor name stand for "extra performance" and serve to stress that the new CPU has been modified and enhanced so that to show higher performance and to allow raising the clock frequencies without any shift to a finer manufacturing technology.

Together with the launching of the new AMD Athlon XP processor family, which took place on October 9, AMD introduced a new CPU naming scheme based on the "performance rating". Therefore, we simply can't help dwelling on this innovation here.

Performance Rating from AMD

To mark different models of the new Athlon XP processor family, AMD decided to use a special rating instead of the processor's actual clock frequency. AMD has already had some similar experience, as well as another processor manufacturer, Cyrix. Both of them were willing to compare their products to those from their major competitor, Intel, as they were built on a much more progressive architecture. Now AMD is guided by similar desires with that only difference that new Athlon architecture is nearly as progressive as that of Pentium 4. However, these two processors are so different that it appears absolutely incorrect to compare their core clock frequencies. The matter is that elder Pentium 4 CPUs do not always manage to outperform elder Athlon processors, despite the fact that their clock frequencies are considerably higher than those of Athlons. Nevertheless, the lack of information pushes many users to prefer Pentium 4 solution, as they are used to believing that higher core frequency always implies faster performance. As a result, some users may appear disappointed with the purchase having spent more money on less performance.

To explain the performance differences between the processors belonging to different classes but working at the same core clock frequencies, AMD introduced the notion of QuantiSpeed architecture. In brief, this term implies that Athlon XP processors with the notorious QuantiSpeed Architecture process more instructions per clock on the average than the CPUs from Intel Pentium 4 family. There is nothing to be surprised at, in fact: NetBurst architecture used in Pentium 4 is optimized for processing streaming data with linear algorithms. In other words, one of the key peculiarities of NetBurst architecture is an extra-long pipeline for commands processing, which allows Pentium 4 processors to work normally at extremely high core frequencies. However, there is another side to the picture. In case of some inevitable errors in the branch prediction algorithm, the CPU has to clear the entire pipeline and decode the program branch anew. As a result, the performance of Pentium 4 processors is not that high though the clock frequencies are really impressive. For example, the diagram below shows the dependence of the performance according to SPECint 2000 benchmark on the core frequency for Athlon and Pentium 4 processors:

As we can see from the diagram, Pentium 4 processors have to work at somewhat higher core frequency to reach the performance equivalent with that shown by Athlon. So, since the processor performance is determined by the core frequency as well as by the average number of instructions processed by the CPU per clock, and AMD Athlon CPUs process definitely more instructions per clock than Pentium 4, the megahertz by AMD and megahertz by Intel turn out two absolutely different things.

This way, trying to make a better impression on the unsophisticated users, AMD made up its mind to introduce a certain performance rating independent of the CPU core frequency. So, from now on all AMD Athlon XP processors will be marker in the following way:

At present, the processor rating values result from the comparison of the new Athlon XP performance with older Athlon (Thunderbird) performance. Here is an example: if we take, for instance, Athlon XP 1800+ CPU, it will work in most applications as fast as some hypothetical Athlon (Thunderbird) 1.8GHz. Of course, we can speak only of some approximate performance equality in most widely spread applications, and we would never grant that Athlon XP 1500+ with the real clock frequency of 1.33GHz will always leave behind Athlon (Thunderbird) 1.4GHz.

As for the users' strong desire to compare new Athlon XP rating to the Pentium 4 working frequencies, AMD doesn't comment on it in any way. But even if we dare make this kind of comparison, it would turn out that AMD had pretty modestly estimated its processors' potential. Even an ordinary Athlon 1.4GHz performs as fast as Intel Pentium 4 2GHz in many applications. So, if we compared AMD's rating with the Pentium 4 working frequencies, it would turn out that Athlon XP 1.53GHz could be compared only to Pentium 4 1.8GHz. It doesn't make any sense, i.e. Athlon XP rating has nothing to do with Pentium4 core clock frequencies.

However, everything is far not so simple. Having taken a closer look at Intel's and AMD's roadmaps we noticed that by the end of Q1 already, Athlon XP rating should grow up to 2200+, while the eldest Pentium 4 CPU available by that time will support 2.2GHz. Another impressive coincidence like that will take place in Q2'02 as well: AMD will offer its new Athlon XP 2400+, and Intel - its Pentium 4 2.4GHz. So, it looks as if AMD were still bearing in mind the possibility to compare its performance rating with Pentium 4 frequency. As for the currently existing "resource", which allows the today's Athlon XP CPUs with the rating equal to Pentium 4 working frequency to outperform the latter, it may get eliminated as soon as Pentium 4 processors move to a new Northwood core. As you remember, it should happen in the beginning of next year. As is known, the L2 cache increased up to 512KB will considerably speed up the Pentium 4 performance, so that the new 0.13micron core will turn out much faster than the currently available Willamette one. This way we dare state that Athlon XP rating introduced by AMD will let compare the performance of the new processors not only with that of the older ones based on Thunderbird core, but also with the performance of future Northwood based Pentium 4 rivals.

Finishing our small discussion of AMD processor rating we would like to touch upon one more interesting thing. AMD will do its best to remove the actual core frequency of its Athlon XP CPUs from our every day use. From now on the CPUs will be marked using the rating only, and the resellers will be obliged to stop using the frequency numbers in their price-lists. Moreover, AMD has already talked to its partners among mainboard manufacturers and warned them that their products will not be certified and hence included into the list of recommended products if the BIOS of these mainboards displays the actual CPU frequency while the system is booting.

AMD Athlon XP CPU: Closer Look

AMD Athlon XP processor is based on the Palomino core, which we have already told you about. Here are its basic specifications:

• Palomino core is made with 0.18micron copper interconnect technology on AMD's Fab30 in Dresden.
• 128KB L1 cache (64KB for data and 64KB for instructions), 256KB on-die L2 cache working at full processor frequency. The L2 cache is exclusive.
• There are the following models in the Athlon XP family now: 1.33GHz (1500+), 1.4GHz (1600+), 1.47GHz (1700+), 1.53GHz (1800+) and 1.6GHz (1900+).
• EV6 system bus working at 266MHz. Socket A physical interface.
• 128sq.mm die size. 37.5 million transistors.

Like all other processors built on Palomino core, Athlon XP features a number of enhancements. In the first place, we should point out two innovations, which made Athlon XP CPUs faster than their Thunderbird based predecessors working at the same core frequency. We are talking about Data Prefetch Mechanism and enhanced Translation Look-aside Buffers (TLB). We have already discussed the principles and advantages of these features in our previous reviews, so now we'd better look how greatly they affect the performance. For this purpose, we will compare the results shown by Athlon on Thunderbird core and by Athlon on the new Palomino core (both processors worked at 1.4GHz):

As you can see from the table, the performance difference between the two cores working at the same frequency hardly exceeds 6%. By the way, a similar performance increase is typical of the Duron CPUs on Morgan core against those on the older Spitfire (see our previous processor reviews for more details).

Of course, we can't leave out the fact that the new Athlon XP processors support 3DNow! Professional instructions compliant with the SSE set. However, it is certainly not enough to simply integrate the SSE support into the CPU: it is also essential that its performance doesn't discourage the developers from making real use of its potential. In order to estimate how fast Athlon XP CPUs fulfill SSE instructions we resorted to SiSoft Sandra 2001 synthetic benchmark. The results for the SSE unit of our Athlons were compared with those shown by Pentium 4 SSE unit.

This benchmark uses an algorithm of building a Mandelbrot Set. So, according to it, the SSE unit of Athlon XP processors is not that bad. In integer operations all Athlon XP CPUs outperformed the eldest Pentium 4 processor working at 2GHz. And in floating point part of the tests they ran neck and neck with the Pentium 4 2GHz CPU. Therefore, we expect Athlon XP to perform really well in those applications, which use SSE instructions, and hence consider the addition of extra SIMD instructions to be a really worthy enhancement.

Also we would like to mention that the new Palomino core boasts 20% lower heat dissipation. By simply redesigning the processor a bit AMD managed not only to reduce the heat dissipation, but also to raise the top frequency of its 0.18micron cores up to 1.73GHz. Just for your reference we would like to offer you a comparative table of the heat dissipation rates for the Athlon XP CPUs and the eldest Athlon (Thunderbird) processors:

Note that now the Athlon XP CPUs feature an integrated thermal diode, which should allow more accurate monitoring of the CPU state.

New Packaging

One more innovation introduced in Palomino based Athlon XP CPUs is the use of new packaging for the processor die to be mounted onto. To get a better idea of the differences between the old and the new solution, take a look at the photo below showing Athlon XP and Athlon (Thunderbird):

Athlon XP (Palomino)	Athlon (Thunderbird)

Now Athlon XP CPUs use OPGA package (organic pin grid array) instead of the formerly used CPGA (ceramic pin grid array). There were several reasons that pushed AMD to this decision. First of all, it was a matter of production costs, as the organic package is considerably cheaper to produce than the ceramic one and provides much better heat dissipation from the processor core. Secondly, - and it seems to be the most important reason - the new package allowed AMD to move the capacitors responsible for clear processor power supply from the top of the CPU package to the bottom part of it, closer to the processor die. The greater will grow the core clock frequency, the more helpful will be this measure, and as soon as the production of Athlon XP CPUs is moved to 0.13micron technology, this decision of AMD's will prove absolutely worth it.

However, the use of organic materials for the processor package is not free from some drawbacks. For example, now that the processor package has become thinner, some old Socket A coolers may turn out unfit for the new Athlon XP fellows as their heatsink won't get pressed tight enough to the processor die.

The second significant disadvantage that is worth mentioning in our review is its greater sensitivity to laser rays, which serve to cut the AMD Golden Bridges. As is known, the clock frequency multiplier of Athlon XP processors is locked. To lock it AMD opens a number of L1 Golden Bridges on top of the processor package. Although AMD started using new CPU package, the mentioned procedure remained unchanged. However now the laser cuts the organic package much deeper, than in case of the ceramic one and hence, it turns out a much harder task for an overclocker to close the bridges properly.

Mainboards and Our Testbed

New Athlon XP processors are designed to support 133MHz FSB (266MHz DDR). AMD will produce no CPU models for a 100MHz bus anymore (remember that for Thunderbird based Athlon processors AMD announced two models: one supporting 100MHz FSB and the other one - 133MHz FSB). That is why the new Athlon XP CPU will not be supported by the older mainboards, which do not allow clocking the FSB to 133MHz. Moreover, to make the Athlon XP work properly you will need a new BIOS, which knows to recognize it. Here we have to point out that almost all the mainboard manufacturer have already released the corresponding BIOS updates for their existing mainboards.

The launching of Athlon XP CPU took place together with the announcements of numerous new mainboards based on VIA KT266A and SiS735 chipsets. It was a very good coincidence, because our tests showed that the mainboards on these chipsets provide the highest performance among all other Socket A DDR platforms. That is why when you face the problem of selecting the mainboard for your Athlon XP based platform, we would recommend you to pay special attention to products on the mentioned above chipsets first, because they offer about 5%-10% higher performance than the boards on any other chipsets.

In particular, for our tests we took VIA KT266A based mainboard from MSI called KT266 Pro2-RU.

Speaking about this mainboard we would like to mention firstly the remarkable stylish outlook, which the board owes to its red PCB. However, it is not only a nice looking product, but also a very stable one with a great number of interesting features.

Besides the broad expansion opportunities, ensured by 3 DIMM slots supporting PC1600/PC2100 DDR SDRAM, an AGP 4x slot, a CNR slot and 5 PCI slots, we should also point out that the mainboard supports an unprecedentedly high number of USB ports: 8. Four of them are implemented via the USB hub built into the chipset South Bridge and support USB 1.1, while the other four ports are provided by the onboard NEC controller supporting USB 2.0.

The mainboard is accompanied by an additional bracket with the 4 USB 2.0 ports and with the so-called D-Bracket with the layout for two more USB 1.1 ports and four light emitting diodes for the D-LED diagnostic system.

Moreover, the mainboard is also equipped with an integrated ATA/100 RAID controller from Promise supporting only RAID 0 or RAID 1 array type.

And finally we would like to draw your attention to one really fun thing featured by MSI KT266 Pro2-RU: MSI Smart Key. This electronic key can be installed into the USB port for some security purposes. Namely, you may appear unable to access the PC without this key or lock the mouse and the keyboard on the fly once the key is removed from the USB port.

As for the overclocking friendly features, KT266 Pro2-RU is a perfect choice. It allows setting the FSB frequency via BIOS Setup equal to any value from 100MHz-164MHz interval, adjusting the CPU clock frequency multiplier and increasing Vcore up to 1.85V and Vdimm up to 2.7V.

Testing Methods

We tested a nearly complete family of Athlon XP processors available in the today's market. We compared the performance of the new AMD processors with that shown by the eldest representative of the previous AMD processor family - Athlon (Thunderbird) 1.4GHz, and with that shown by their No.1 competitor - Intel Pentium 4 2GHz. All Socket A CPUs were tested on MSI KT266 Pro2-RU mainboard on VIA KT266A DDR chipset described above. Pentium 4 processor was tested on i850 based mainboard from ABIT - TH7II.

We would like to stress that from now on we will use a faster graphics card in our testbed. It is GeForce3 Ti 500.

As a result, our testbeds looked as follows:

All the tests were run in two operation systems: Windows 98 SE for office and gaming benchmarks and Windows2000 SP2 for professional and scientific benchmarks.

Performance

In business applications, which make the essence of this benchmark, actually, Athlon XP CPUs appear quite fast leaving behind Intel Pentium 4 2GHz. Nothing to be surprised at: Athlon processors featuring a relatively large L2 cache have always been the winners here. It is a totally different thing that is of interest to us in this benchmark: Athlon 1.4GHz managed to outperform Athlon XP 1500+, which definitely disputes the new AMD's performance rating. However, you shouldn't forget that the actual working frequency of the Athlon XP 1500+ CPU makes 1.33GHz, which means that the enhancements introduced to the Palomino core do not affect the performance in office tasks. Look here: Data Prefetch Mechanism and enhanced Translation Look-aside Buffers influence only the work with the memory, making it faster. The common office applications do not require processing large data blocks and using complex algorithms. That is why it is pretty logical that both: the new Athlon XP and the older Athlon (Thunderbird) working at the same core clock frequencies performed on equal level.

The applications used in Content Creation Winstone 2001 benchmark set do profit a little bit from the enhancements made to Palomino core that is why Athlon XP proves somewhat faster than the regular Athlon working at the same core frequency. However, Athlon XP working at 1.33GHz is still behind Athlon 1.4GHz. As for Pentium 4 2GHz CPU, its speed can be compared only with the performance of younger Athlon XP models.

SYSmark2001 is more loyal to Intel CPUs that is why Pentium 4 2GHz won all the laurels. However, we have already mentioned the reasons for this victory, which appear even clearer if we take a look at the following diagram:

Internet Content Creation tests include Windows Media Encoder 7.0, which doesn't use SSE instructions supported by Athlon XP because of some bug. This is exactly what makes these CPUs fall behind Intel competitor. And in the meanwhile that Microsoft hasn't launched a new version of this software, which defines the SSE support correctly, we decided to leave the results of this benchmark "as is".

As for the office part of SYSmark2001, the situation is totally different and elder Athlon XP CPUs easily outperform the fastest Pentium 4 working at 2GHz. By the way, note that Athlon 1.4GHz on Thunderbird core proves faster than the youngest Athlon XP 1500+ (1.33GHz) in all office tests.

To make the office coverage complete, we measured how fast the systems could archive the data packs of big size (directories with installed Unreal Tournament) with the maximum compression, which loads the CPU quite heavily. For this purpose we used a widely-spread WinZIP archiving utility. So, the smaller value on the diagram denotes higher performance. As a result, Athlon XP 1800+ turned out 7% faster than Pentium 4 2GHz.

The situation is absolutely the same for the DVD video stream encoding into DivX MPEG-4 format. Here we would also like to note that Data Prefetch Mechanism and enhanced Translation Look-aside Buffers play a highly positive role for the video encoding procedure, as they help Athlon XP to leave its predecessor on Thunderbird core far behind. Working at the same 1.4GHz clock frequency Athlon XP appears almost 11% faster than Athlon (Thunderbird).

This gaming benchmark is historically very favorable for Pentium 4 CPUs, which prove really impressive there. The announcement of Athlon XP family has hardly changed anything: Pentium 4 2GHz remains the leader here. But the gap between the leader and the eldest Athlon XP 1800+ is no longer that huge: only 6%.

Another game, Unreal Tournament, shows a totally different state of things. Pentium 4 2GHz turns out beaten by the common Athlon 1.4GHz, not to mention the rest of the Athlon XP family.

Dronez benchmark is very similar to Quake3, though much more hypertrophied. Due to thorough optimization for SSE2 and high memory bus bandwidth, Pentium 4 2GHz proves an indisputable leader.

The results in 3DMark2001 are equal for Athlon XP and Pentium 4 processors.

However, as soon as you disable hardware T&L unit, Athlon XP processors rush forward. This phenomenon can be explained by the fact that the SIMD-instructions unit gets loaded much heavier during the transformations and lighting calculations carried out by the CPU. And as we have shown before, Athlon XP performs SSE-instructions fast enough. This is exactly the reason why the situation differs so greatly from the previous case.

As usual, we tested Athlon XP in scientific applications aimed at solving some problems of math1ematical modeling. Of course, Athlon XP processors showed their best. As is known, in tasks of the kind the performance of the floating-point unit is of great importance, and that is one of Athlon's strengths. Three-pipeline FPU of this processor lets it surpass Pentium 4 without any effort. To illustrate this statement take a look at the diagram. According to the benchmark results, Athlon XP 1800+ appears 17% faster than Pentium 4 2GHz.

If we go into details of the previous test, we will see that Athlon XP is not always faster then Pentium 4 in scientific tasks. For example, in Primodia test based on solving Shredinger equation for all the 61 electrons of Promethium element, Pentium 4 2GHz outperforms the entire Athlon XP family. This benchmark requires higher memory bus bandwidth rather than faster arithmetic co-processor, that is why Pentium 4 turns out quite at home in this benchmark as well as in all other applications operating large data packs intensively.

To check the performance of our testing participants during 3ds max 4 final rendering, we measured the time needed to render the Anisotropic Wheel scene in 800x600 resolution mode. Accordingly, the shortest time stands for the best result. We have already pointed out in our articles that rendering in 3ds max is a purely arithmetical task, and that is where the performance of the arithmetic co-processor matters a lot. The results prove once again that Athlon XP processors are beyond any competition, just like in ScienceMark.

However, in ViewPorts the situation changes drastically. Pentium 4 is no longer in the very end. It even manages to catch up with Athlon XP 1800+ showing competitive performance.

And in conclusion we would like offer you a couple of tests from the professional SPECviewperf 6.1.2 package. The results of this benchmark are not influenced by the graphics card performance. That is why we can get a very clear picture. The entire Athlon XP family beats Pentium 4 2GHz in DesignReview test imitating the work of 3D modeling application.

Although Pentium 4 2GHz runs faster than its AMD competitors due to its fast system bus in IBM Visualization Data Explorer, we should nevertheless give credit to AMD. In fact, the enhancements of the Palomino core have a really incredible effect. When working at the same core frequency, Palomino turns almost 20% faster than Thunderbird. Luckily AMD didn't base its performance on the results of this benchmark :-)

In Lightscape Visualization System from Discreet Logic Pentium 4 again takes the lead.

Conclusion

Well, a quick look at the diagrams is enough to state that Athlon XP is currently the fastest x86 CPU. AMD Athlon XP 1800+ together with VIA KT266A based mainboard outperforms Intel Pentium 4 2GHz in most benchmarks. So, AMD again managed to win the laurels of processor performance.

However, we should also bear in mind that next year Athlon XP family will have to compete with a more powerful rival: Pentium 4 Northwood. These CPUs will feature twice as large L2 cache as that of the today's Willamette, which may shake Athlon XP's positions considerably. But, let's nor rush ahead of time, as AMD also doesn't keep its hands in pockets and is working on the new Thoroughbred core, due next year.

Anyway, we have just seen that AMD is strong enough to compete with Intel Pentium 4 for a long time despite all hardships.