The combination of these events led Cyrix to begin losing money, and the company merged with National Semiconductor on 11 November 1997.

This processor continued the Cyrix tradition of making faster replacements for Intel designed sockets.

Initially, Cyrix tried to charge a premium for the Cyrix-claimed extra performance, but the 6x86's math coprocessor was not as fast as that in the Intel Pentium.

Unlike previous 3D games, Quake used the pipelined Pentium FPU to do perspective correction calculations in the background while texture mapping, effectively doing two tasks at once.

This would not have been a big problem for the 6x86 if, by that time, Quake had a fallback to do perspective correction without the FPU as in, for example, the game Descent.

Quake also lacked the option to disable perspective correction, thus eliminating that potential speed boost for FPU-weak CPUs.

The Cyrix MII, based on the 6x86MX design, was little more than a name change intended to help the chip compete better with the Pentium II.

In 1996, Cyrix released the MediaGX CPU, which integrated all of the major discrete components of a PC, including sound and video, onto one chip.

Initially based on the old 5x86 technology and running at 120 or 133 MHz, its performance was widely criticized but its low price made it successful.

Cyrix developed the Cayenne core as an evolution of the 6x86MX/MII processor, with dual issue FPU, support for 3DNow instructions and a 256 KB, 8-way associative, on-die L2 cache.

[13][14] It is unclear how advanced development on this core was when Cyrix was acquired from National Semiconductor by VIA Technologies and the project discontinued.

Legal action from Intel, who objected to the use of the strings "P166" and "P200" in non-Pentium products, led to Cyrix adding the letter "R" to its names.

The PR nomenclature was controversial because while Cyrix's chips generally outperformed Intel's when running productivity applications, on a clock-for-clock basis its chips were slower for floating point operations, so the PR system performed more poorly when running the newest games.

In the early days, Cyrix mostly used Texas Instruments production facilities and SGS Thomson (now STMicroelectronics).

Cyrix's designs were the result of meticulous in-house reverse engineering, and often made significant advances in the technology while still being socket compatible with Intel's products.

[15][full citation needed] Intel lost the Cyrix case, which included multiple lawsuits in both federal and state courts in Texas.

In the end after all appeals, the courts ruled that Cyrix had the right to produce their own x86 designs in any foundry that held an Intel license.

This provided Cyrix with an extra marketing arm and access to National Semiconductor fabrication plants, which were originally constructed to produce RAM and high-speed telecommunications equipment.

Since the manufacture of RAM and CPUs are similar, industry analysts at the time believed the marriage made sense.

The IBM manufacturing agreement remained for a while longer, but Cyrix eventually switched all their production over to National's plant.

The merger also resulted in a change of emphasis: National Semiconductor's priority was single-chip budget devices like the MediaGX, rather than higher-performance chips like the 6x86 and MII.

Whether National Semiconductor doubted Cyrix's ability to produce high-performance chips or feared competing with Intel at the high end of the market is open to debate.

The MediaGX, with no direct competition in the marketplace and with continual pressure on OEMs to release lower-cost PCs, looked like the safer bet.

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.

Meanwhile, the MediaGX faced pressure from Intel's and AMD's budget chips, which also continued to get less expensive while offering greater performance.

The last Cyrix-badged microprocessor was the Cyrix MII-433GP which ran at 300 MHz (100 × 3) and performed faster than an AMD K6/2-300 on FPU calculations (as benched with Dr. Hardware).

By the time National Semiconductor sold Cyrix to VIA Technologies, the design team was no more and the market for the MII had disappeared.

"[17] National Semiconductor retained the MediaGX design for a few more years, renaming it the Geode and hoping to sell it as an integrated processor.

Although the company was short-lived and the brand name is no longer actively used by its current owner, Cyrix's competition with Intel created the market for budget CPUs, which cut the average selling price of PCs and ultimately forced Intel to release its Celeron line of budget processors and cut the prices of its faster processors more quickly in order to compete.