| AMD K6-III AMD K6 CPU has been launched in April 1997 and it has been the first CPU on the market of the sixth generation followed, a month later, by Intel Pentium II. This processor soon showed high performance with integer calculations (at that time the competitors were Intel Pentium MMX and Pentium PRO CPUs as well as the new Pentium II), with performance with floating point calculations as choke point. In June 1998 the model K6-2 has been introduced with some difference in comparison to K6.
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Production process at 0.25 microns: to be true this technology has already been implemented in the versions at 266 and 300 MHz of K6 available on the market starting from April 1998, but these are not popular on the market. -
Bus frequency at 100 MHz: K6-2 has been the first Socket 7 CPU to support this bus frequency with advantages in terms of general performance. -
Introduction of 3DNow! instruction set: to reduce the performance gap with game applications in comparison to Intel CPU, AMD introduced a set of 24 instructions called 3DNow! within the CPU Core. The introduction of 3DNow! instructions represented the first innovation in the x86 architecture since its introduction. In February 1999 there has been the third evolution of the K6 series, with the 
introduction of K6-III model; this CPU has been created integrating 256 Kbytes of L2 cache within the Core of K6-2 CPU. Following are listed the technical details of the two CPUs. K6-2 K6-III Socket Socket 7 Socket 7 L1 Cache 64 Kbytes (32K data; 32K istructions) 64 Kbytes (32K data; 32K istructions) L2 Cache from 512Kbytes to 2 Mbytes, depending on the motherboard used, working at bus frequency 256 Kbytes, inside the cpu Core; working at clock frequency L3 Cache - from 512Kbytes to 2 Mbytes, depending on the motherboard used, working at bus frequency Core voltage 2.2V (2.4V for 450 and 475 Mhz versions) 2.4V Clock frequency 300-333-350-366 380-400-450-475 Mhz 400-450 Mhz Bus frequency 95Mhz; 100 Mhz 100 Mhz Core type CXT CXT K6-III CPUs must be installed on Super 7 motherboards, that is those including following requirements: Note how all the Super 7 motherboards for K6-2 CPUs, if including power voltage of 2.4 V, can use K6-III CPU too after updating the BIOS. There are some problems connected to the electrical features of the CPU; due to the integration of the L2 cache within the CPU Core, the requirements for a processor have been increased in comparison to K6-2, as shown here: K6-2 K6-III Current 7.35A (266 Mhz) 8.45A (300 Mhz) 9.40A (333 Mhz) 9.85A (350 Mhz) 10.30A (366 Mhz) 10.70A (380 Mhz) 11.25A (400 Mhz) 12.50A (450 Mhz) 13.00A (475 Mhz) 12.40A (400 Mhz) 13.50A (450 Mhz) Maximum heat dissipation 14.70W (266 Mhz) 17.20W (300 Mhz) 19.00W (333 Mhz) 19.95W (350 Mhz) 20.80W (366 Mhz) 21.60W (380 Mhz) 22.70W (400 Mhz) 28.40W (450 Mhz) 29.60W (475 Mhz) 26.80W (400Mhz) 29.50W (450 Mhz) Medium heat dissipation 8.85W (266 Mhz) 10.35W (300 Mhz) 11.40W (333 Mhz) 11.98W (350 Mhz) 12.48W (366 Mhz) 12.95W (380 Mhz) 13.65W (400 Mhz) 17.05W (450 Mhz) 17.75W (475 Mhz) 16.10W (400Mhz) 17.70W (450 Mhz) Note the increased maximum heat dissipation (the maximum values remains however the same as K6, that is 233 MHz working at 3.3V with a value of 30.2W), which can be explained both with power voltage increased at 2.4V and high clock frequency as well as the power maximum request which achieves 13.5 Amperes with version at 450 MHz of clock.
It is important to check the Super 7 motherboards, above all if one of the first manufactured, to see if they can be used with K6-III CPUs; the readme file of the newest version of the BIOS must be read in orther to do this. The certification for K6-III CPU ensures that the electrical part of the motherboard matches the power requirements of the K6-III so to avoid stability problems and misbehaviours. K6-III CPU can also been installed on some Socket 7 motherboards including Intel 430HX and 430TX chipset with power voltage at 2.4V; these motherboards don't include bus frequency of 100 MHz, but this doesn't affect the performance as we can see in the following illustration: Setting the 2x multiplier of the motherboard (multiplier included in all Socket 7 motherboards), the CPU multiplies at 6x so to obtain the clock frequency of 400 MHz (66x6) similar to what happens with K6 CPU and Pentium MMX which turn on the 3.5x multiplier when the 1.5x motherboard is set. Is necessary to visit the Web site of the manufacturer and check the certification for K6-III (always with the problem above said of the maximum power), as well as the presence of a BIOS update which detects the CPU. Using the 3DNow! instructions allows to speed up a series of operations related to 3D graphics with an increase of frame per second displayed by a 3D scene; this doesn't happen with all kind of software, but 3DNow! instruction need to be supported. This can be done in three ways: -
Implementation of instructions within the graphic engine of the application, code of the program: in this way you obtain the best performance even if it is difficult to implement as you need to set again the code of the application or use 3DNow! instructions from the beginning. The same results can be obtained using upgrading patches specifically designed. -
DirectX 6: Microsoft API supports for 3DNow! starting from the version number 6; the limit to increase the performance is to see how the application programmers chose to use DirectX features which exploit the presence of 3DNow!. -
Video driver: as the 3DNow! instructions are specific to speed the 3D graphic, you can implement them within the driver of the video accelerator; this is the easiest way to implement, but performance doesn't increase a lot. The main limit of the 3DNow! instructions is a wide machine range (that is a number of PC including 3DNow! CPU) but a limited range of software. It is possible to see with games software. Microsoft API DirectX support 3DNow! instructions starting from the version number 6, but often game programmers don't use them or only partially; it refers to a more efficient support of the 3DNow! instructions starting from the version number 7 of DirectX. Practically, with 3DNow! instructions there is an increase of 10-15% of fps with DirectX 6 programs even if the patch for Quake 2 (a very popular game developed with 3D technology) specifically designed by AMD shows how the gain in performance can be higher if the instructions are used in the correct way: Using a 3dfx VooDoo 2 SLI accelerator is possible to note an increase in performance, about 68% more at a resolution of 800x600 and 65% at a resolution of 1024x768 using K6-III CPUs; using a Riva TNT accelerator, the gain in performance is lower, between 15% and 20% depending on the resolution. Using 3DNow! instructions with the rendering software leads to an increase in general performance even if limited to 12-14%; anyone use nowadays rendering through software, but this kind of test can show the average increase that we can expect turning on the 3DNow! instructions. 3D Mark Max benchmark allows to check the impact of 3DNow! instructions in rendering the polygons of the 3D scenes; turning on 3DNow! instructions lead to an increase in performance changing from 150% and 180%, a very high value. These data are only theoretical values as it can't be reproduced with real applications, but they clearly show how the appropriate 3DNow! instructions can speed up the processing of the geometry of the scene. Using 3DNow! instructions doesn't affect only the increase of displayed fps; in fact if there are games requiring many fps to be played (such as Quake 2), there are some other which need less frames per second (think to graphical adventures); in these cases, 3DNow! instructions enrich a 3D scene, more details are displayed to increase realism without changing the number of frames displayed (more processing power available, more polygons inserted in the scene and processed by the CPU, more detailed scene). Pentium III Pentium II has been launched at the end of April 1997; at the very beginning of that month AMD had launched the first x86 6th generation cpu, the K6, but Pentium II has soon become the fastest CPU available, both for clock frequency and general performance. There are many improvements from Pentium MMX (launched in January 1997): -
The connection to the motherboard isn't based on Socket 7 but on Slot 1; this is due to the need of integrating the L2 cache on the CPU (but not within the Core), but we can say that this change is really based on marketing reasons (Slot 1 has Intel copyright so other manufacturers can't use it unless they are licensed to). -
The L2 cache isn't related to bus frequency but to clock frequency (in particular, it works at half of clock frequency): we have seen how the working frequency of the L2 cache is an essential component for general performance; moving the L2 cache directly on the CPU, Intel managed to obtain a performance gain and a quite constant increase of performance as the clock frequency increases. -
Floating point unit taken from Pentium PRO CPU: higher performance with floating point calculations have been the most powerful aspect of this CPU in comparison to competitors, both AMD K6 and Intel Pentium (together with an higher clock frequency) which led to use it with High-End. Pentium II has been launched with clock frequencies of 233 and 266 MHz, followed by the 300 MHz version in September 1997; in January 1998 the version at 333 MHz was launched and it was the first CPU using a production process at 0.25 microns against the 0.35 microns of previous versions; this leads to distinguish two types of Core used for Intel Pentium II CPUs: Klamath at 0.35 microns and Deshutes at 0.25 microns. In April 1998 the version at 350 and 400 MHz of clock frequency have been launched, with bus at 100 Mhz, while in September 1998 the version at 450 MHz of clock frequency has been introduced. In February 1999 the Intel Pentium III CPU has been officially presented, available at 450 and 500 MHz of clock frequency: following are listed the main features of these CPUs: Pentium II Pentium III Slot type Slot 1 Slot 1 Cache L1 32 Kbytes (16K data; 16K instructions) 32 Kbytes (16K data; 16K instructions) Cache L2 512 Kbytes 512 Kbytes Core voltage 2.0V - 2.8V 2.0V Clock frequency 233-266-300-333-350-400-450 Mhz 450-500 Mhz Bus frequency 66Mhz; 100 Mhz 100 Mhz Core type Klamath (233-266-300 Mhz) Deshutes (333-350-400-450 Mhz) Deshutes Following are listed the electrical features of the processor: Pentium III Current 14.5A (450 Mhz) 16.1A (500 Mhz) Maximum heat dissipation 25.3W (266 Mhz) 28.0W (300 Mhz) It can seem that Pentium II and Pentium III are, except for the clock frequency, the same, but it isn't true: in Pentium III 70 new instructions have been introduced, called SSE (Streaming SIMD Extensions), which speed up 3D, videoconferencing and multimedia programs. In detail, they can be divided in three groups: -
50 instructions work in SIMD (Single Instruction Multiple Data) mode, so they can apply the same instruction to many data at once speeding up the 3D graphic performance; -
12 extensions of the MMX set of instructions (which was launched with Intel MMX CPU in January 1997) and work specifically with video rendering; -
8 instructions allow the software to control the data flow from the system memory to the processor, through the processor memory avoiding the cache memory to put a side data which have to be used again with performance gain. From this comes that the software has to use all the 70 instructions, as it happens with 3DNow! instructions of AMD K6-2 and K6-III CPUs. This can be made in different ways: integrating the necessary code within the software (3D application or game), support through the driver of the video card (for the instructions which speed up the running of 3D applications) or through API Microsoft DirectX 6.1. Nowadays there are only few applications which use SSE instructions, so we can't forecast the spreading of these in houses' software; it is true that when they are used the performance increases as shown in these examples: The CPU 3D Mark test included in the 3D Mark 99 Max benchmark allows to check the impact of SSE instructions on the calculation process of the geometry of a 3D scene; note how using these instructions the performance increases of 62%. Another benchmark which shows that the performance increases when using the SSE instructions is Lightning and Transformation included within the 3D Winbench 99 version 1.1 of Ziff-Davis; the performance obtained by Celeron at 500 MHz is the same of an ideal Pentium III at 500 MHz without SSE instructions. Note how the performance increases of 72%, a very high value; the limit of these data is the fact that they refer to ideal situations which can't be reproduced in real life. One of the main features of Pentium III is a serial code which allows to identify the processor used; following there is a screenshot of the utility which allows to display the serial code. There have been many arguments on this feature of Pentium III: it is technically possible, in fact, that someone reads the serial code while you are online (such as when you visit a site) without noting it and this led Intel to disable the default serial code. It is difficult to understand why Intel introduced such a feature, except for the fact that it allows to identify the processor thanks to the serial code. |