After Intel has launched Pentium III, AMD in its turn also introduced its new achievement - K6-III processor. This newprocessor was supposed to raise AMD from the low-cost systems market and to let it compete with Intel as an equal in a moreexpensive market. In fact, this new CPU should pave the way for the main blow against the microprocessor giant with its K7blockbuster. Long and breathless expectation, preliminarily posted specifications and first impressions of AMD K6-III madeus believe that Intel should dread the coming weakening of its position. But as usual AMD is playing the part of a pursuer,and to win this fight it certainly needs significant fire superiority compared to its opponent. However, we can announce anew round of AMD against Intel, Socket7 against Slot1, David against Goliath.

Well, let's see what AMD is offering. Here are the technical specifications of AMD K6-III:

• 0.25 micron chip;
• CXT core, which is a usual K6-2 core with a Write Combining feature;
• Fits for Socket-7 mainboards, however requires BIOS update;
• 64KB L1 cache, 32KB for instructions and 32KB for data;
• 256KB L2 on-chip cache;
• Mainboard cache working as L3 cache;
• Core voltage 2.3-2.5V (this value can differ in various supplies);
• A set of 21 3DNow! SIMD-instructions. There are two pipelines operating with 2 pairs of single precision real numbers;
• A range of CPU frequencies: 350, 400, 450 and 475MHz. FSB frequency - 100MHz (95MHz for 475MHz CPU frequency).66MHz FSB frequency is also acceptable;
• 3DNow! supported by DirectX 6.0 and up.

The specifications show that AMD K6-III is none other than an AMD K6-2 plus core integrated 256KB L2 cache working onCPU frequency. Taking into account great performance shown by Intel Celeron, we have every reason to hope that AMD K6-IIIwill also demonstrate a significant performance improvement because the weakest point of the system - memory bus, though itoperates at 100MHz, - is now powered by cache. Besides, L2 cache in K6-III is twice as big as in Celeron, and twice as fast(though twice as small) as in Pentium II. Moreover, you shouldn't forget about the cache integrated on the mainboard - itturns into L3 cache and adds a bit more to the performance level.

Besides, there is another thing, which is worth our precious attention - the three letters CXT in the core name.This core has recently appeared in K6-2 processors and differs from its predecessor only by a Write Combining function.In other words the new core allows to transfer data through the bus not spontaneously, but consecutively in 8-byte sets assoon as they are completed. This strategy provides a slight performance gain while transferring data through 64-bit bus.However, this function can hardly be called a new one because Write Combining has been present in all Intel's CPU's starting fromPentium Pro.

As for 3DNow!, there aren't any changes compared to K6-2. However, we have to admit that not many applications, which arenowadays available in the market, utilize this technology, and 3DNow! support in graphics cards drivers and DirectX doesn'tprovide any effect. As in case with SSE, you have to use SIMD-instructions for 3D-geometry parameters calculating to get aconsiderable performance increase because the DirectX optimized functions are not fast enough and aren't used by the developers.

This promising introduction makes us believe that Intel will be able to compete with AMD only after it launches itsCoppermine - a new core in Pentium II/Pentium III family. Let us remind you that Coppermine will also have 256KB L2 cacheworking on core frequency, and maybe also 64KB L1 cache. Besides, this new core will contain Intel SSE SIMD-instructionssupport. So, it is safe to say that AMD got the start of Intel this time at least in terms of L1 and L2 cache sizeas well as in terms of 3DNow! launching date since AMD was the first to do it.

So, the only specs parameter, which is AMD's serious drawback in comparison with Intel Celeron/Pentium II/Pentium III,is a relatively slow non-pipeline arithmetical FPU used for calculations, particularly in a plenty of games. AMD firmly statedits position concerning this matter as soon as they launched K6-2: they expected that FPU would fall into oblivion if favorof 3DNow!. But for the time being these expectations haven't yet come true. If K6-III with its slow FPU and a cool cache willmanage to do better than Intel's processors, we'll see from the tests.

Besides, we'd like to point out the fact that the new K6-III will be successfully supported by old Socket7 mainboardswhich have a BIOS version with CXT core support and which allow to set core voltage equal to 2.3-2.5V. However, if themainboard user's manual doesn't describe the way of setting this voltage, don't give way to despair. There are undocumentedvoltage settings in most cases.

The first thing that aroused our sincere interest was the speed achieved while working with cache memory of variouslevels and with system memory. To check this we tested 4 different CPUs: AMD K6-2, AMD K6-III, Intel Celeron and IntelPentium II working at the same frequency - 450MHz (100 x 4.5). The results turned out to be very intriguing:

We see that L2 cache of K6-III works much faster than that of Celeron. However, this small victory is as usual overshadowedby AMD's low performance in system memory tests, which is partially due to Socket7 chipsets manufacturers. But ifwe take into account that transferring exceedingly big amounts of data (over 256KB) is a rather rare occasion, it becomes clearthat this disadvantage doesn't influence the general processor speed that much, and AMD really hoped for it when installing anadditional high-speed L2 cache into its processor.

Now let's pas over to the main tests. The testing system was configured as follows:

• AMD K6-2 400, AMD K6-III 400, Intel Pentium III 400 and 450, and Intel Celeron 300A and 400 CPU;
• Chaintech 6BTM and Chaintech 5AGM2 mainboards;
• ASUS V3400TNT graphics board (on a Nvidia Riva TNT chipset) with Detonator drivers;
• 3D-accelerator Creative 3D Blaster Voodoo2;
• Soundcard on Ensoniq ES1370 chipset;
• IBM Titan DTTA 371010 harddisk;
• 128MB SEC PC-100 SDRAM;
• Windows98;
• all 3D-tests were run with 800x600x16 resolution.

First of all we considered the performance in office applications:

Here K6-III proved up to our expectations and showed great results. Actually, this has always been like that: AMDprocessors are very good at operating integers, which dominate in the office applications. CPUMark99 test for integeroperation measuring once again proves this statement:

Yes, that's true, K6-III deserves being called "the best integer CPU". The same test demonstrates a tangibleperformance gain due to the added quick L2 cache in comparison with AMD K6-2. But unfortunately, FPU working speed,which is a thorn in its side, is of the same great importance, especially in games.

Well, we'd better not see it. As it comes to real arithmetic AMD turns out absolutely helpless. A non-pipelined FPUmakes itself felt and hence makes your recent admiration vanish in the twinkling of an eye. Luckily, AMD is planning tototally replace the FPU block in its next offspring K7 CPU, which gives us hope for the better as far as future AMD CPUsare concerned.

However, almost all CPUs find their main application in games, which require extremely high computing capacity.We utilized CPU 3Dmark included into 3Dmark 99 MAX testing package to evaluate CPU performance while working out parametersfor 3D-scenes. This test calculates 3D-geometry but displays no result on the screen. This allows to get CPU top performancein 3D games disregarding the type of the graphics card. With K6-2 and K6-III we tested both possible options: when 3DNow! blockis on and then off.

The results strike as very curious. The first thing that catches your eye is a twofold gain of AMD K6-III performancewhen 3DNow! is on. To our great disappointment, this result is reached because of the slow FPU rather than due to very fastSIMD-instructions. Actually, AMD foresaw that software developers would prefer 3DNow! to FPU. In practice it provesquite reasonable since K6-2 (and of course, K6-III) SIMD-instructions work much faster than a co-processor that is whyif possible, i.e. if there is a 3DNow!, most calculations are readdressed to it from the arithmetic FPU. In other words,when 3DNow! is on you can avoid the main impediment in 3D-scenes calculating - the co-processor and hence you can witnessan incredibly fast performance.

The next thing also can't remain unnoticed. If you take use of 3DNow! optimization, K6-III will turn out the quickestCPU. It means that general high-quality optimization under 3DNow! is required and everything again depends on game-developers,otherwise K6-III will fail to win the leadership. But unfortunately, there aren't many optimized applications available now.And as for DirectX, it appears to be of absolutely no use because its optimized instructions are hardly utilized by anyone.The situation seems likely to change as soon as DirectX7 comes out, at least Microsoft has promised to change the API core sothat it could become acceptable for game developers.

Nevertheless, let's have a look at the performance of the new CPU in real games. The first turn belongs to Quake2. Sometime ago this game was specially optimized for this particular CPU and used to demonstrate AMD 3DNow! features. So, we ranmassive1 test for both options: optimization on and off. Here are the results obtained through 3dfx OpenGL miniport:

Well, the results are not so optimistic, as with synthetic CPU 3Dmark test but still K6-III stands on its dignity.K6-III 400 with the enabled 3DNow! shows the performance equal to that of Intel Pentium II 450. But as soon as this blockis put into the "off" position fps number drops by almost 1.5 times and you can hardly speak of any competition.

However, if Riva TNT OpenGL-driver is used the situation turns out slightly different:

In this case 3DNow! hardly brought any tangible gain - a couple fps can't be regarded as a competitive result. So, aconclusion inevitably comes to mind: it is none other than bad Riva TNT drivers optimization that spoils the whole picture.

Now let's try K6-III in Unreal, which is considered to be the "hardest" game of the day for any CPU because of thepoor 3DNow! optimization.

Here K6-III proved to be quite good though it is still not up to Pentium II results.

The general picture starts getting clear - everything depends on optimization. No optimization - no performance.That's why those who are willing to use a CPU with 3DNow! should keep pace with the time and frequently visit AMD site inorder to refresh their list of corresponding games.

The next issue we found worth tackling was the influence of on-board L3 cache size on the system's generalperformance. TriLevel Cache architecture (i.e. 3 caches in a single system) is an item of AMD's special concern. Should westrive for larger caches on the mainboard? To answer this question we offer you the following results chart:

Now the answer seems evident: a large cache doesn't necessarily mean good performance. Over 1MB cache on your system boardgets you practically no performance gain.

And now a few words about overclocking. Those two AMD K6-III 400 samples we'd got for testing came from differentsupplies and were extremely unwilling to operate at the frequency exceeding their stated one. Though their clock multiplieris not locked these processors have almost no frequency stability. By the way, the core voltage officially increased by 0.2Vindicates the same fact - AMD has practically exhausted the opportunities of 0.25 micron technology and this increase is thelast try to achieve higher CPU outcome. That is why now only 0.18 micron processors are expected to work overclockingwonders.

Conclusions

So, it turns out that AMD K6-III is presently the quickest CPU (speaking only about x86 family) for integer operations.In other words, its cool performance in the majority of office applications will greatly impress you (only if you are capableof noticing such changes in Ms Word, for instance :) Of course, this shouldn't make you immediately shift from Slot1 to Socket7because real arithmetic still causes some problems by AMD. If you are guided by some other reasons, as the possibility of playingnew games at high speeds then all that matters is 3DNow! technology support. If the application is appropriately optimized thenyou'll get high CPU performance. But at the same time you should bear in mind that Voodoo with its cool SIMD support is the best3D accelerator for AMD K6-III by now. So, generally, the new processor makes a good choice for your K6-2 upgrade.

And to conclude with, let us remind you once again that the next AMD CPU is promised to be free from K6-III main drawback -slow FPU. Besides, the system bus is also about to undergo several changes. And hence, if K7 comes out in time it will be a greatproduct! And for today Intel Celeron still remains the best thing to purchase at least until AMD K6-III becomes available atthe price of K6-2.