National Semiconductor ran into financial trouble soon after the Cyrix merger, and these problems hurt Cyrix as well. By 1999, AMD and Intel were leapfrogging one another in clock speeds, reaching 450 MHz and beyond, while Cyrix took almost a year to push the MII from PR-300 to PR-333. Neither chip actually ran at 300+ MHz. A problem suffered by many of the MII models was that they used a non-standard 83 MHz bus. The vast majority of Socket 7 motherboards used a fixed 1/2 divider to clock the PCI bus, normally at 30 MHz or 33 MHz. With the MII's 83 MHz bus, this resulted in the PCI bus running alarmingly out-of-spec at 41.5 MHz. At this speed, many PCI devices could become unstable or fail to operate. Some motherboards supported a 1/3 divider, which resulted in the Cyrix PCI bus running at 27.7 MHz. This was more stable, but adversely affected system performance. The problem was only fixed in the final few models, which supported a 100 MHz bus. Almost all of the 6x86 line produced a large amount of heat, and required quite large (for the time) heatsink/fan combinations to run properly. There was also a problem which made the 6x86 incompatible with the then-popular Sound Blaster AWE64 sound card. Only 32 of its potential 64-voice polyphony could be utilized, as the WaveSynth/WG software synthesizer relied on a Pentium-specific instruction which the 6x86 lacked. Meanwhile, the MediaGX faced pressure from Intel's and AMD's budget chips, which also continued to get less expensive while offering greater performance. Cyrix, whose processors had been considered a performance product in 1996, had fallen to the mid-range, then to the entry level, and then to the fringe of the entry level, and was in danger of completely losing its market.
national semiconductor ran into financial trouble soon after the cyrix merger and these problems hurt cyrix as well by 1999 amd and intel were leapfrogging one another in clock speeds reaching 450 mhz and beyond while cyrix took almost a year to push the mii from pr-300 to pr-333 neither chip actually ran at 300+ mhz a problem suffered by many of the mii models was that they used a non-standard 83 mhz bus the vast majority of socket 7 motherboards used a fixed 1/2 divider to clock the pci bus normally at 30 mhz or 33 mhz with the mii's 83 mhz bus this resulted in the pci bus running alarmingly out-of-spec at 415 mhz at this speed many pci devices could become unstable or fail to operate some motherboards supported a 1/3 divider which resulted in the cyrix pci bus running at 277 mhz this was more stable but adversely affected system performance the problem was only fixed in the final few models which supported a 100 mhz bus almost all of the 6x86 line produced a large amount of heat and required quite large (for the time) heatsink/fan combinations to run properly there was also a problem which made the 6x86 incompatible with the then-popular sound blaster awe64 sound card only 32 of its potential 64-voice polyphony could be utilized as the wavesynth/wg software synthesizer relied on a pentium-specific instruction which the 6x86 lacked meanwhile the mediagx faced pressure from intel's and amd's budget chips which also continued to get less expensive while offering greater performance cyrix whose processors had been considered a performance product in 1996 had fallen to the mid-range then to the entry level and then to the fringe of the entry level and was in danger of completely losing its market