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Low end processors from the 1990s

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Avatar for Geri
Written by   99
1 year ago
Topics: Technology, Tech

I planned to make a test about low-end computers from the late 90s. Actually, more a processor test than a computer test. Instead of gathering various computers, i will use the same Socket7 based computer. Socket7 is a platform that supports low-end processors of the late 90's. Socket7 is also backwards compatible with Socket5 processors. To perform this test, i will use the same Socket7 based computer platform, and i will swap out the processors. I planned to benchmark all of the popular Socket5/7 processors. Difficulties showed up, so i was only able to measure certain payloads on certain CPUs. After an accidental cmos clear, system reinstall became inevitable. I was indeed able to test all of these processors, just not with the same program. Partially, the reason was, that in some cases, some program or even some hardware was incompatible with certain CPU instruction sets. Therefore, instead of numerical benchmark results, i will explain what can be expected from the various CPU models.

About the Socket7 platform

The Socket7 is a never version of Socket5. Originally, the platform was developed for the Intel Pentium1 processors. Unlike nowadays, when every CPU manufacturer makes processors for totally different CPU sockets and motherboards, in the 90s, every manufacturer used the same CPU sockets (with some exception). The later 486 based computers used the Socket3, and then the Socket7 (Socket5) overtook the market. Socket7 based computers were the most popular computers not just at the end of the 90s, but also at the beginning of the 2000s. These computers were used even in 2005-2006 in some countries as family computers.

Picture: A typical Socket7 motherboard

Socket 5 appears

The Pentium1 first was released for the Socket4. However, the Socket4 had some issues, and it quickly got removed from the market. Intel redesigned the specifications a bit, and then the Socket5 was made. These first Socket5 based Pentium1 processors ran maximum at 133 MHz, but as far as a i know, the 90 MHz models were the most popular. 100 MHz models were also available at least on paper. Models at 75 MHz was also existed (actually i have one, but it is not going to be tested, as my motherboards are not compatible with that). Socket 5 motherboards usually had integrated AT keyboard connector, a standard AT power supply connector, two IDE controllers, two, four or six EDO memory slots, a floppy controller, and sometimes, even an integrated video card. 3 or 4 ISA and 2 or 3 PCI slots were usually also included.

Other manufacturers

AMD also released its processor for the platform. Cyrix followed, and then IDT and Rise Technologies also released its processor for this platform. The platform got renamed to Socket7 later on, as the platform got SD RAM and 100 MHz FSB, and later it get support for AGP (Super Socket7). Originally the platform had support for 50 MHz, 60 MHz and 66 MHz FSB (front side bus speed). The memory is always clocked at the speed of the FSB, so if the FSB is for example, 66 MHz, then the memory will run at 66 MHz as well. The CPU will multiply the speed of the FSB based on the multiplier settings. Later motherboards added 75 and 83 MHz FSB speeds, and the final models introduced 100 MHz. (VIA also released a chipset which was able to do 133 MHz FSB). AMD clinged to this platform for the longest time, and the fastest CPU they have released reached 550 MHz.

Non-Socket7 motherboards

I have decided not to test non-socket7 based computers from the era. At the end of the 90s, two other motherboard design also became popular. One was the Socket370, which was the platform for Intel Celeron processors. The second was the Slot1, which was designed for the Pentium2 processors. Later on, the Pentium3 CPU family was released for both of these. Socket8 was the platform for server rigs, and used by the Pentium Pro and by some Pentium2 overdrive chips. None of these platforms will be tested, as they were midrange and high-end, and this test will focus on the low-end solutions.

What made Socket5 and Socket7 popular

Socket5/7 was sold in large numbers, so it made a lot of sense from the CPU manufacturers to have backwards compatibility. Newer Socket7 motherboards were also designed to be compatible with the older Socket5 based processors, so people was able to use even their old CPU and sometimes even their old RAM, as later motherboards had both EDO RAM and SD RAM slots. The backwards and forwards compatibility of these hardware made it possible to upgrade an aging computer with a CPU that was multiple times faster than the original CPU in the system. As most of the early Socket5 computers had PCI port, people was even able to add 3D video cards and modern high-end sound cards and multimedia accelerators, IO controller cards, TV capture cards to them.

Limitations of Socket7

Socket5 and Socket7 was initially designed in 1994/1995, and despite of newer and newer motherboards, CPU-s, the limitations quickly started to plague the platform. One of the problems was the limited HDD support. Back then, most motherboards didnt supported bigger than 4 GByte hard drives. This was not a problem in the 90s, as the hard disks were barely larger than 1 GByte. But in early 2000s, 10-20GB hard disks became the standard. Some manufacturers fixed this by BIOS upgrade, some did'nt care. Older motherboards of course had no AGP, so if someone wanted to play games on these computers, had a harder time hunting down decent 3D cards for the PCI socket. Getting memory was also harder, and EDO memory was usually only available in 4 and 8 MByte sticks. If the motherboard had an SD memory slot, then it was far easyer to find SD memory with the size of 16 and 32 MByte memory sticks, but bigger memory sticks were also supported on newer motherboards.

A typical Socket7 based computer

Most Socket5/Socket7 based computers came with AT and in horizontal computer case. As they were screw-compatible with 486 computers, they was usually built into 486 cases, after throwing out the old motherboard from them. But towers and ATX based Socket7 motherboards were also available. Socket7 based computers usually had 16, 32 or 64 MByte memory. They had a CD drive, a floppy drive, an ISA-based sound card, a video card. One or two hard disks from 800 MByte to 4 GByte was the most popular choice as storage. Later models had 64 or 128 MByte memory, sometimes, even 256 MByte, and one or two 10 GByte hard drive. The speed of the processors varied, from 90 MHz to 550 MHz, and now, we are going to take a look of all the popular processors of this platform.

The 486 based systems

The 486 architecture was aging like milk. The memory system was too slow, and even if these was CPUs above 66 MHz available for the 486 platform, they were not able to profit too much from the extra clock speeds. Overwhelming majority of 486 motherboards only had ISA slots with bulky, chunky and slow expansion cards. Usually even the hard disk controllers were placed on ISA or VLB slots. Most 486 motherboards were supporting 8 MByte RAM, which wasnt even that plenty for Windows 3.1. It became clear for Intel and the other x86 manufacturers, that the time has been passed over the 486, and even if some later 486 boards was equipped with PCI and onboard IDE, the other limitations was too hard to be wrestled down. 486 was also manufactured by various companies, however most of the 486 chips were licensed clone of the Intel 486 (at that time, Intel licensed its CPU designs, and every company was able to manufacture compatible chips).

RISC based non-x86 processors

Competitors were starting to build RISC processors already exceeding 100 MHz, and the future of x86 became questionable. Despite of writing software for the x86 for decades, the software industry started to place bets on MIPS, and they was thinking to ditch x86 and Intel. The x86 instruction set was CISC, this meant that instructions encapsulated multiple operations - such as stack handling, memory addressing, memory displacement, quick operations with other registers, and the arithmetic operation itself as well. RISC CPU architectures were the opposite of this - they used very simple instructions. This technology allowed them to be clocked at high clock speeds compared to x86. Also, RISC CPUs were superscalar - this meant they had multiple execution pipelines, so they were able to execute multiple instructions at the same time. Even if they needed more instructions to do the same mathematical operation as x86, this design made them very fast. Corporations like Toshiba, NEC, Philips, LSI started to use the MIPS architecture for their high-end computer systems, and they planned to enter the consumer market with these computers, threatening the x86-based home computer ecosystem. Even Windows NT got ported to them. Intel, AMD and other x86 manufacturers had to move fast.

The arrival of the Intel Pentium

The first samples made into markets in 1993 but the architecture really caught up after 1994. The Intel Pentium (Intel Pentium 1) shocked the competitors. x86 was not a laughing stock any more, in fact, it grabbed the RISC processors by their neck. The public tought its impossible to implement a superscalar CISC processor, but Intel just did that. Intel seriously redesigned the execution pipeline of the 486, and they have added two of them to the same core. This means that the Pentium was now able to execute two instructions within one clock. They had a notable cache memory to store these instructions, and operation as well, and they have increased the memory data bus from 32 bit to 64 bit, which meant that the effective bandwidth of the memory to the CPU was doubled.

The test

The computer i will use in this test, is based on an Asus P5A-B Super Socket 7 motherboard. I will use a 2 GByte large hard disk, an old DVD drive (a CD drive would be more fitting, but will not alter the results of the test). This computer have 768 MByte installed, which is not standard for the late 1990s, as then people used 32 or 64 MByte RAM, and even in the early 2000s, more than 256 MByte was unusual. But i will still not replace the memory just for the sake of the test, as it will not alter the results, and i would have problems to properly re-seat the RAM modules to the sockets. As newer nVidia video card drivers can not work without MMX, i will use a 3Dlabs Permedi2 PCI 4 MByte VIVO video card to perform the test, which will work fine with all of the processors in this test, and also has very good 3D acceleration.

Intel Pentium1

This is not the first Pentium 1 processor, and not even my oldest Pentium 1 processor, but older ones will not work in my motherboard as it lacks the 50 MHz FSB. This can be considered the first wide-spread Pentium1 CPU. And indeed the CPU offered brutal performance for its era. The superscalar in-order design, the monstrous L1 cache and FPU allowed this CPU to create the new era of entertainment. The Pentium 1 has 16 KByte cache memory, and consumes 9 Watts. The processor needs 3.3V and some people used it partially passively, but i will install a proper heatsink with a fan on it. The CPU was below 10$ on the second-hand market in 1999. It made sense to buy it, or replacing it made a big difference? How this 1994-made 5 year old CPU performs in 1999? We will find it out.

I planned to clock this CPU to 90 MHz, to 100 MHz and to 133 MHz. And oops, guess what, the 133 MHz model didnt booted up. I had to swap it out to the 100 MHz model. Luckily, previously i already have tested the 133 MHz model, so i have test results from it. On 90 and 100 MHz, this CPU is basically a terrifyingly weak CPU for late 90s. Of course, it was fantastic for 1995, it just aged like milk. Prepare for 100%ish mp3 playback CPU usage and sound stuttering, if you was not lucky with your sound card. This also means that video playback is out of the question (mpeg uses mp3 encoded audio streams as well). At least Debian Linux works fine on this chip, but very slowly. The 133 MHz version is more interesting. that allows good mp3 playback, and video playback is now enjoyable in 320x240. Rumors say the Pentium 133 can be overclocked to 150 or 166 MHz, if you have a motherboard that can support the 75 or 83 (85) MHz FSB. Bigger multipliers are out of the question. If your model will run at these clock speeds, then you was very lucky, because suddenly everything gets a brutal boost. Suddenly, 288p videos will start to work, but you will be far from just being able to listen an mp3 file in the background meanwhile you doing some computing intensive task. For gaming, you want the overclock for sure, the 133 MHz model will not be usable for it, but the 166 MHz model with the 83 MHz FSB will just do it for you, pushing you over from unusability to the edge of usability. For this type of overclock, the ceramic model is recommended, the gold capped models seem like older revisions, which dont scale that well. Fun fact, i have a 75 MHz model from this CPU, which is rated for 50 MHz FSB and 1.5x multiplier. I dont know what was the idea behind that, or what motherboard could be able to accept that, as i have never seen any with 50 MHz FSB. Sadly, that will not even boot on 90 MHz, but if you come across of that model, do not expect anything from that model. nVidia cards, such as the TNT1 are out of the question when using this CPU, as it will not work properly with a non-MMX CPU. The original Pentium1 is a boring and quite useless CPU for the Socket7, and you indeed want to replace it to something more usable model.


AMD wanted to make a worthy competitor of the Pentium. Previously, AMD used Intel designs, but from the Pentium line, Intel decided not to sell the Pentium design to anyone. AMD had no x86 line on their own, but AMD had a RISC cpu family. AMD came up with the idea to use this design even for an x86 CPU, which they have heavily modifyed for this purpose. AMD didnt wanted to leave Intel alone on the market for this caliber of CPU technology, so they have released their line of Socket7 processor with the same parameters as Intel did. The CPU uses 3.5v (which is about the same as Intels 3.3v and they are interchangible anyway). The CPU however lacks some of the new instruction set of the Pentium, so the programs will usually think this CPU is a 486. Despite of this, the AMD also used a very tricky CPU architecture in this CPU. Internally, this CPU is a RISC processor, which got x86 decoder units. Within the CPU, there is a microcode based hardware accelerated x86 emulator embedded, to run regular x86 programs. That was never been tried before in the industry! The K5 was released in 1995, but actually it only made to the markets in 1996 in production quantities. The power consumption of this CPU is about 12W so it indeed requires an active cooling. The cache memory is 24 KByte, which is bigger than the cache of Intel Pentium1, but the bigger cache is probably needed to store the decoded instructions produced by the x86->RISC translation layer. Will this engineering miracle from AMD be able to compete with the Pentium 1? Its important to note that this CPU was also priced below $10 in 1999ish second hand markets. Funny enough, my model has a sticker, saying, its an AMD K5 PRO, and was sold for $3 in the early 2000s.

The CPU i have can work at 90 or 100 MHz in the test. And indeed, the performance is the same as the Pentium 1. Smooth video playback is however not possible above 320x240. I dont have the 133 MHz model, but i have dubts if it would make too much difference. The AMD K5 has issues booting most of Linux distributions. The boot process usually hangs when the initrd is being decompressed. The CPU has a weird hardware bug that causes glitches and CRC errors when decompressing certain files. Maybe my model is fauly, and another chip would work properly, i have'nt tested this with different processor. Sadly both the 90 and 100 MHz model is too slow for anything usable. MP3 encoding, decoding, multimedia usage is out of the question. Some programs will think this CPU is just a 486 and refuse to run. Programs compiled with gcc has to use the -march=i586 flag, the i686 will cause crash. This means that almost no programs compiled after 2006, or so, will run on this CPU, as the gcc from that date uses i686 code profile by default. This CPU has a strange FPU issue, it seems the FPU precisity is one bit less than what it should be. This causing strange issues in some software renderers, and even in some hardware renderers sometimes.

Cyrix 6x86L

The Cyrix 6x86 was a monolithic x86 CISC CPU from Cyrix. Cyrix already competed against Intel on the 486 front with its own 5x86 design. The 6x86 CPU was lacking most of the Pentium features, but Cyrix followed a very similar path as Intel did. They have built a superscalar CPU based on their older design, with two instruction pipelines. The chip was manufactured in the factories of IBM and ST. IBM and ST was also able to release this CPU under its own logo, as IBM 6x86 / ST 6x86. Cyrix claimed that their CPU is faster than Intel Pentium1 on the same clock speeds, so instead of advertising the processor with their clock speed, they invented the Pentium-rating (which they have quickly renamed to Performance-rating to avoid lawsuits). For example, their Cyrix 6x86 PR133 model runs actually at 110 MHz. Cyrix CPUs use funly FSB speeds with standard multipliers, which arent even widely supported. Therefore, these CPU-s will always be clocked at standard FSB speeds, such as 66 or 100 MHz, regardless of what Cyrix was intended for these processors. Sadly i don't have the original 6x86 but i have the 6x86L, which is the new revision with decreased power consumption and a few more Pentium era instructions for better compatibility. Cyrix targeted this CPU to be a cheap multipurpose multimedia processor for both office and home-use, however in the first time when they was offering faster CPUs than Intel, they have attempted to ask the price of the extra performance. At this time, Quake fanboys were screeching on message boards about the low performance of Cyrix 6x86 solutions under gaming (practicularly under Quake). We will see if its true and not, althrough Quake will not be tested (because probably nobody ran it back then anyway). We will see, how this CPU performs across all type of payloads, and we will see if there will be any issues with stability, as there was rumors about the questionable realibility of these products. Cyrix 6x86 generates more heat than the previous two processors - it can produce 15-20W under full load. The 6x86L however has lower voltage, and consumes about 13-15W which makes it a little bit less demanding. Of course active cooling is inevitable for these processors, with a relatively large heatsink and a fast fan, by 90s standards. The CPU was also priced below 10$ on the second-hand markets so it can be directly compared to the K5 and Pentium1.

I planned to test this CPU at multiple speed, but i was only able to make it work at 133 MHz. Despite the CPU was rated at 150 MHz (PR200) it was only stable at 133 MHz, or maybe the motherboard was unable to supply a stable 75 MHz FSB. The Cyrix 6x86L is sadly very weak. Even with a 3D accelerator, it canot play games very well. Croc1 ran, for example, at 7 fps in hardware accelerated mode. The only exception are Glide based games, but even those will stutter. The 150 MHz settings resulted instability, which have managed to kill my Windows install, making me to almost give up on the review! Most of multimedia programs, such as modern video player software like mplayer, refused to work with this CPU. This means that the built in windows media player was used, which was only able to play 320x240 videos without stuttering too much. This CPU needs half hours to encode a 6 minute long mp3 file. Even playing mp3 files in winamp hogs the system, resulting a good 80% cpu usage. This CPU will not be able to run newer builds of Windows XP, as Microsoft discontinued the support for it due to hardware bugs. The 6x86L was a terrifying experience, which i only recommend if you are really mazochist. Its however certainly a better choice than an AMD K5, especially if you can make it run at 150 MHz with the higher FSB settings. Its rarity also adds up value here, making it more unique than a K5 or P1. Strange enough, it has the same FPU bug as the AMD K5, and it seems it has one bit less precisity of FPU. Linux distributions will also crash at initrd. From a kernel aspect, this is basically a 486 CPU, with Pentium 1 like benefits only in user mode.

Intel Pentium MMX

After the success of the original Pentium 1, Intel redesigned the core quite a bit. They kept the same Socket, and released a new CPU which offers notale boost in performance. The Pentium MMX introduced a new instruction set extension called MMX. MMX offers an integer SIMD unit which can do an arithmetic operation on multiple registers at the same time. To use the MMX instructions, the programs had to be upgraded. MMX is not the only feature of the new Pentium MMX processor. They have decreased the voltage of the processor, to make it consume less on higher clocks. 166 MHz, 200 MHz and 233 MHz models were also available from this CPU family. They have increased the cache memory to 64 KByte. The later CPUs were built with plastic encapsulation, and these models also happened to overclock well. In fact, usually even the 166 MHz unit can be overclocked to 250 MHz or above, as internally, it seems, all the Pentium MMX models are identical. Some early MMX models were also built with ceramic encapsulation, usually from the 166 MHz models. The CPU is more or less compatible with the first generation of the Socket5 motherboards as well, if the motherboards can supply 2.8V for them. The CPU eats about 15W which means they will require active cooling.

I have checked this CPU at 166, 233 and 250 MHz (and 100 MHz FSB was used for the 200 and 250 MHz clock). This CPU has better cache system than other players in this test, as the speed does not collapses so rapidly when the FSB is switched back to 66 MHz from 100 MHz. I have tested this CPU at 133 MHz as well, to compare it with the original P1. And indeed, even on the same clock speeds, this new model offers a good 25% boost. The 166 MHz model can be overclocked to 233 or 250 MHz. Even 200 MHz will boost the maximum watchable video resolution from 288p to 320p, and above 200 MHz, you can get a fluid gaming experience in games like Croc in d3d mode. The CPU is very stable, it can run all version of Windows XP, and it will also boot Debian Linux. I have noticed no glitches so far. One interesting note is that clocking the CPU from 166 to 200 MHz gives a far bigger boost than 200 to 250 MHz, which usually barely gives any notable extra performance in most applications. It seems most Socket7 system can't really scale beyond this point, no matter what you do - after all, there is no L2 cache in the CPU, only the motherboard has some, with questionable performance benefits. Therefore i recommend not to run these CPUs above 250 MHz even if its possible, as there will be no benefits from it (these CPUs can go up to 280 MHz in most situations, which is totally overkill). Instead of trying pushing the limits of the CPU, try to fine tune the FSB, memory timings, io delays, which can give you some more precious percents than just focusing on the CPU itself.

NexGen 5x86

The NexGen was the first competitior of the original Pentium1. It was not a Socket 7 CPU, and i dont have any. Therefore, this CPU is not going to be included in the test. The company used its own CPU Socket, and it was built to low-end systems. Most of the motherboards had not even PCI slots, and it was very obsolete compared to Socket7. The company used a similar approach as AMD. The CPU DIE size was too big, so they had to release the FPU (floating point unit) separately. In later revisions, they have integrated the FPU unit to the CPU unit as well, but the company was not able to survive the initial fiasco, and got bought by AMD.

AMD K6/2

The K6 was built from the legacy of AMD K5 with the help of the NexGen team's upcoming design. The K6/2 is the secondary iteration of the CPU, which is going to be included in this test - as i have none of the first revision. The K6/2 includes MMX support as well. AMD also added a new SIMD unit called 3dnow!, which was a little bit similar to MMX, however it works on floating point vectors. 3dnow! got mostly used in graphics drivers and some video games, where it was able to give some notable speed-up, but it was not widely adapted in normal programs. The AMD K6/2 begins at 200 MHz, and the fastest model made is 550 MHz. The CPU uses 2.2V but some of the models maybe use 2.3V instead. Depending on the model, the K6/2 consumes about 15-20W, so it needs active cooling, especially under higher clock speeds. The CPU has 64 KByte cache memory. The CPU was released for brand new for about 100$ in 1998, and around the end of 99, it was available on the second hand markets for about $50. This means the AMD K6/2 was significantly more expensive than the other Socket7 competitors on the market, however the clock speeds are also bigger. Will be this CPU much faster than the others, which makes it a good buy, or could you just use the previous Intel or Cyrix chips? We will see it. Although on the market, the 350MHz models were the most popular, those can be easily clocked at 400 MHz and sometimes 450 MHz as well, we will see how the CPU scales with the higher clock speeds in this architecture. Its important to note that AMD released K6/3 and K6/2+ models as well. Those CPUs have L2 cache (128 KByte or 256 KByte) to encounter the problems caused by the slow system bus. They are however rare, and i dont have any. They was'nt even that popular.

At 250 MHz, the Pentium MMX was a little bit faster than the K6/2, but at that point the K6/2 already can do the same things as the Pentium MMX. Its interesting to see that the K6/2 barely scales when its clocked at 350 MHz, and it brings almost no extra performance at 500 MHz in most software. In some software, such as compressing, encryption, and so on, the speed benefit from 500 MHz is more notable. In games, usually, there is not much of a speed benefit. Nintendo64, SNES, and Play Station 1 emulators are totally fluid at 400 MHz when using the proper plugins, video and sound cards. This makes (made) the CPU to be a better choice than the Pentium1 MMX which just barely have enough performance to run these titles enjoyable. The drawback is the compatibility. Meanwhile there was no issues with video playback, multimedia, and emulators, there was more problems with older games. Some games just simpmly refused to run, such as Formula One. Built in graphics drivers of Windows98 just simply dont work on the K6/2. The Rage2+ had serious color artifacting, the Virge had instant crashing from every 3D contect. Only after upgrading to the newest drivers, these bugs gone away. Some 3dfx cards also having issues if early drivers are being used. Its important to note that Windows 95 will not boot on highly clocked AMD K6/2 processors as well, so in that case, the clock speed should be downlocked to 233 MHz. Once everything is upgraded, patched, the K6/2 will offer the best performance of this platform (not counting the K6/3 chips). On the higher clocked models (450 MHz or above), mpeg files are playable in 640x480 with special player software, but not with the built in Windows Media Player. With the Cyberling PowerLink DVD software, DVD discs can be also played even at 720x480/720x576. The K6/2 was indeed a worthy competitor, and if someone wanted to push the Socket7 system to the limits, he was able to do so with this CPU. But the gaming performance did'nt increased well with this CPU, as the Socket7 platform just too slow to feed the CPU and the video card for early 2000s games. Debian Linux runs fine on this chip, the desktop performance in Linux is also very good if you combine this chip with a 3D card as well.

Cyrix 6x86MX (Cyrix M2)

Cyrix upgraded its 6x86L processor, and the new chip was called the 6x86MX. Its the same as the previous CPU-s, so its still a monolithic x86 CPU. The CPU also has MMX support. They have also made the FPU a little bit faster. They have upgraded the cache memory to 64 KByte, similarly to the Pentium MMX and K6/2. Unlike AMD, Cyrix was not able to rise the CPU clock speeds such significantly. The 6x86MX was sold with every random speed rating and used funky FSB speeds like the previous 6x86 designs. In reality, most of the chips was running at 166 MHz, 200 MHz, and if you were lucky, you was able to overclock it to 233 MHz or 250 MHz. Its almost impossible to find faster models than these. The chip was manufactured by IBM and sometimes on IBM models it is being referred as 6x86MX-2. The chip also exists as Cyrix M2, which is the same chip, they just renamed it to follow the naming convention of the Intel Pentium2 line. The 6x86MX got some new instructions, and instructionset-wise, its halfway between the Pentium MMX and Pentium2 line. The chip uses 2.9V and consumes a good 20-25W power. 2.2V versions were also available. This CPU was cheaper than AMD and Intel CPUs. The 166 MHz model was available for $50-$60 which is about half as much as the 80-100$ price tag of the 166 Mhz Pentium1 MMX CPU. The faster models were also priced half as much as the AMD K6/2 models. This is however due to the lower performance, and not due to the clever design or manufacturing process. Cyrix had trouble selling these processors at higher price range, so they had to keep the CPU prices low. This eventually led to the demise of the company, which was bought by National Semiconductor later on, and later they got bought up by VIA. But was this CPU really that bad? We will see the results from the tests. It can be hard to hunt down this CPU nowadays, as gold melters have discovered it has notable gold inside it, so most of the Cyrix CPUs out of the wild got destroyed. Luckily i was able to gather these chips before this.

I have tested the CPU at 133 MHz, 166 MHz, 200 MHz, and 250 MHz (200 and 250 with 100 MHz FSB). The Cyrix 6x86MX, despite of its bad reputation, is actually a very strong CPU, if you manage to run the chip above 200 MHz. To unleash this strong power, however, 100 MHz FSB is needed. With third party video player programs, such as mplyer, it can even play 360p mpeg video files. Users was allow to listen to mp3 files while working on their computer without too much slow-down. At 250 MHz, it only consumes 30% CPU time to play mp3 files. Gaming is a nice experience. The 166 MHz models are sadly not that good, and if you manage to find a CPU that can run at 200 MHz, it will perform better if you can use the higher FSB speeds. Once the FSB is big enough, the RAM timings are small as possible, the performance gives you a totally fluid user experience (from an 1999-ish eye, of course). This CPU indeed allowed you to do all kind of professional work, play, enjoy multimedia content, and its rock stable. I have experienced no incompatibility with any software, and everything performed as you would expect. In hardware rendering, Croc1 ran at 18 fps on the overclocked model with 100 MHz FSB with a Riva128. On 200 MHz with 66 MHz FSB, it already fell to 15 fps. The slower models can only run it at 13 fps. In glide, the speed reaches 25-30 fps, but the speed still falls on the sub 200 MHz models. JPG encoding needs fast FSB as well. This CPU canot reach the speed of the K6/2 or the Pentium1 MMX on the same clock speeds, but its very close. In some cases, its better choice to choose the 6x86MX over the K6/2 or the Pentium1 MMX, such as when someone plans to use the computer for gaming. Older games, unline on the K6/2, are starting up without problem. The strange FPU issues of the 6x86L are the thing of the past, the 6x86MX is indeed made for low-end gaming and office-type usage. Sadly, its not too ideal for multimedia consumption compared to the K6/2, and it had to compete against the Pentium1 MMX with its cheaper prices.

IDT WinChip

IDT was manufacturing MIPS processors. They had a subdiary at the corporation, called Centaur. This group was workig on emulators. They have designed the emulation layer for the corporation, to execute x86 code on MIPS. Later on, they have used this knowledge to redesign the CPU core a little bit. The IDT WinChip is a heavily redesigned MIPS CPU that got a hardware accelerated x86 decoder unit. It follows a similar approach to AMD k5/k6/NexGen processors, which are similarly to the WinChip, also hardware accelerated x86 emulators. The chip was designed to be a low-cost, low-power office and multimedia PC. The WinChip group released several variations of this CPU. The original release is called IDT WinChip (C6) which i have bought just for the sake of this test. The CPU is capable of MMX, and its usually running at 200 MHz. Models with other clock speeds are also available, which i have never seen. It has 64 KByte cache. WinChip2 also exists, which supports AMDs 3dnow! instruction set. Its not that rare, but i have never seen any. In West Europe and in USA, it was probably more popular. Its a funny side story that IDT had a HQ in Hungary, and the workers once got WinChip for christmas. They did'nt knew what to do with it, so they used it to scrape the dandruff from their scalp. Too bad, as only seven millions of this CPU was manufactured in total, so it can be a little bit rare to find nowadays. The CPU is compatible with even the earlyest Socket5 motherboards, as it uses 3.5V. This CPU will be tested on 200 MHz and 233 MHz. It has a little bit funky multiplier and FSB support, and it does not supports most of the standard multipliers, so it is going to be tricky to make it running. It consumes about 13-15W, and it was available for $130 price at introduction, which probably fell very quickly as the performance is not going to be such shiny.

Or will it be? Well, certainly not. This CPU is a potato. Even at 200 MHz, i had to cheer this CPU not to die from 240p video playback. I had to play with this CPU for almost 30 minutes to make it work. I had to re-seat it in the socket, till it was finally booting up, at 66x3 = 200 MHz settings. The results were shocking. About twice as slow performance in encryption, decription, in compressing, compared to the Cyrix 6x86 @ 250 was quite a shock to see. The clock to clock performance of this CPU is actually lower than anything else in this test, including the first generation K5 and the Pentium1. Buying this CPU instantly makes a sense, when someone wants to use it in an early motherboard. As the CPU runs at 3.5V, it can be used in first gen Socket5 motherboards, so they can be updated with this CPU. The high clock speeds solve the problem of the low IPC, if the user can find the proper jumper settings, which are usually the following: you try random multipliers till it somehow boots up, and the speed is at least 200 MHz. Once it booted up, its in pair with a severly overclocked Pentium1. As it has MMX, the multimedia applications will run on this CPU as well. Well, the 360p videos are out of the question. nVidia cards will work with this CPU, just there is no raw performance to beat even a Pentium1 MMX-166 MHz model. The K6/2 at 500 MHz was about 4 times faster than the WinChip at 200 MHz, especially in compression and encryption (such as AES). When its about games, do not expect anything to be very playable in D3D, only in Glide. If someone manages to run this CPU with 75 MHz or 80 MHz FSB, that will probably solve some of these performance issues (i wasnt so far, but of course its not impossible). After that, the CPU would reach the performance of a Cyrix 6x86MX around 180 MHz... too bad the CPU only allows a tiny little bit of overclocking headroom, about 75x3=225 MHz. Lucky people can overclock the WinChip C6 to 250 Mhz with 83 Mhz FSB and x3 multiplier, getting out 250 MHz, but it will usually result an unstable CPU.

Rise MP6

Another Socket7 competitor was the Rise MP6. The Rise MP6 was a low-cost, low-power CPU. It supports MMX and 100 MHz FSB speeds. The CPU was usually released at 200 MHz clock rate. I don't have any of this CPU, but its important to note that this CPU was also existing for this platform. It was less common than all of the designs above. Some models are branded as Rise iDragon. It runs at 2.8V or 2.7V, and it consumes about 15 Watts. The CPU uses similar conception to Cyrix. Its a monolithic a superscalar x86 CPU design, with three integer and two floating point units. Rise claimed it can perform similarly as the Pentium2 on the same clock frequencies, but i have serious dubts about that. The CPU was sold in small numbers, and it was retiring the market a year after the introducion of this CPU. The chip only have 16 KByte cache memory, which burdens the performance. The chip was sold to SiS, who later sold it to DP&M who used it as a basis for its Vortex86 design, which i have, but it is not going to be included in this test, as those are late 2000s models.

In overall

The Pentium MMX and the Cyrix 6x86MX will give you a very nice experience on 250 MHz, when using 100 MHz FSB. The Pentium MMX clock by clock is faster than the Cyrix, but back then it was far more expensive, and its not that much faster. Of course, the Pentium MMX will also slow down, when 66 MHz FSB is being used. Therefore, increasing the FSB is recommended to get decent performance out from the system. Nowadays the Pentium MMX CPU is easy to get, and all the models, even the 166 MHz models, are usually rock stable even at 250 MHz. The Cyrix 6x86MX is a little bit hard to get, but it worths the price as well, as the CPU even can boot newer operating systems.

The Cyrix 6x86L is not recommended. Its a buggy CPU, and it has issues with most of the newer operating systems. If its only used from Win9x, it can be a good choice if this is the only CPU to upgrade to. However, the motherboard should support the 75 MHz FSB to get some notable performance out of it, compared to the Pentium1 or K5 processors.

The K5 and Pentium1 processors are not recommended. These are very weak processors compared to the demand of the late 1990s-ish software, games, and programs. Programs will think that the K5 is a very fast glorified 486 CPU, and even the Pentium1 is very far from being able to deliver a fluid Winamp-era entertainment for you, unless you find a model that can be overclocked significantly.

The IDT WinChip is only recommended if you want to upgrade your super old Socket5 based system, which does not support Socket7 CPU-s for some reason. This reason could be the lack of dual plane voltage, so the motherboard can only deliver 3,5V voltage to the CPU. Then this CPU will indeed work very better than the K5 or the Pentium1, especially if you can find 75 MHz FSB settings on your motherboard.

The K6/2 is recommended, if you want a good multimedia experience from your retro machine. Using the K6/2 will give you nice video playback abilities. Operating vintage TV tuner cards with MPEG video capture is also the territorry of the K6/2. Running vintage CAD or CAM programs, converting, recording, playing something old media back, will also work with this chip. Vintage gaming could have issues, so for that purpose, the 6x86MX and Pentium1 MMX is more recommended than this.

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Written by   99
1 year ago
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it's good and very informative topic.

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1 year ago

Things to read, Geri!

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1 year ago

Wow! A very comprehensive technical review on the evolution of low-performance processors of the '90s. I wonder, what can you do with these today? Perhaps, develop a school project or any practical use in the home for those who like to do it yourself.

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1 year ago

basically, nothing. the only actual user case of these is to run old software + old hardware. plenty of old games and old 3d cards for example, will not run on modern hardware, or on emulators

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1 year ago

basically, nothing. the only actual user case of these is to run old software + old hardware. plenty of old games and old 3d cards for example, will not run on modern hardware, or on emulators

Ok! Although I think that always there are people, lovers of the past, and the knowing. Thank you for sharing this review.

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1 year ago

Very nice, i like that processors too

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1 year ago