Last Updated on January 23, 2026 by Dave Farquhar
AMD launched its K6-2 microprocessor on May 28, 1998, a little over a year after its predecessor, the K6. The K6-2 built upon the K6, increasing performance to better compete with the Pentium II. Since it still used the Socket 7 architecture, and Socket 7 motherboards had provision for cache on the board, the motherboard cache served as a level 3 cache.
AMD K6 vs K6-2
Like the AMD K6, the K6-2 is based on the Nx686 microprocessor that NexGen was designing when AMD acquired it in 1996. AMD manufactured the K6-2 using a 250 nanometer process and it had 9.3 million transistors. The K6-2 ran at 2.2 volts. It enhanced the K6 in three major ways:
- Increasing the front side bus to 95 or 100 MHz
- Adding 3DNow instructions to better compete with MMX
- Running at faster clock speeds, up to 400 MHz at launch, eventually reaching 550 MHz
3Dnow: SIMD before SSE
AMD also cooperated with Cyrix and IDT to create 3Dnow, the first non-Intel extension of the x86 instruction set. 3Dnow’s SIMD instructions extended MMX, compensating for the weaker floating point performance in the K6-2 and other non-Intel CPUs. It was similar to, but incompatible with, Intel’s SSE instructions included in the Pentium III. Software that used 3Dnow instead of the floating point unit could execute up to four times faster.
Tom’s Hardware Guide found Nvidia‘s Riva128 driver, which used 3Dnow, allowed the K6-2 to punch above its weight in terms of 3D performance. The 333 MHz K6-2 performed nearly the same as a 400 MHz Pentium II at launch.
Software had to specifically support 3Dnow and unfortunately, with a few notable exceptions, it never gained much support. In August 2010, AMD dropped 3Dnow except for its PREFETCH and PREFETCHW instructions.
The AMD K6-2’s faster front side bus
AMD cooperated with third-party makers of Socket 7 chipsets to increase the bus speed to a maximum of 100 MHz. Intel Socket 7 chipsets officially only supported a maximum of 66 MHz, although overclocking them to 83 MHz was common practice among power users. Cyrix shipped Socket 7 CPUs using these bus speeds, but they resulted in overclocking the PCI bus. The new Super Socket 7 chipsets ran the PCI bus at 1/3 the CPU front side bus to stay within the PCI spec.
The 95 MHz bus problem
K6-2s that ran on the 95 MHz bus, such as the 333, 380, 427.5, and 475 MHz versions, weren’t popular with enthusiasts. Enthusiasts who were willing to buy an AMD CPU, perhaps because they had an accelerated graphics card like a 3dfx or Nvidia, wanted the 100 MHz front side bus and the 33 MHz PCI bus. But system makers eagerly used the 333 MHz K6-2. Consumers didn’t really know the difference, and the 333 MHz version of the Pentium II used a 66 MHz front side bus. When Tom’s Hardware Guide benchmarked the K6-2 on its release date, it found the K6-2 ran business applications at a very similar speed to the Pentium II at 333 MHz.
O’Reilly’s book PC Hardware in a Nutshell speculated that most people who bought 333 MHz K6-2s overclocked them. But the author of that book forgot about the OEM market. Prebuilt mass market PCs were still very popular, and OEMs like IBM and Compaq were willing to use whatever AMD or Intel CPU let them meet a desired price point.
Competition with Intel
The AMD K6 gave Intel a more serious threat than it was used to, and Intel responded in several ways. It started cutting prices aggressively. And it attacked AMD on both fronts. The inexpensive Celeron CPU attacked AMD at the low end. And on the high end, Intel increased the front side bus on its high-end Pentium IIs to 100 MHz. These actions forced AMD downmarket without ceding the low end of the market entirely to AMD.
AMD priced the K6-2 between $185 and $369 at launch time. AMD had a policy of pricing its chips 25 percent below Intel’s closest equivalent. But Intel responded with aggressive price cuts, making that difficult to maintain. AMD kept the K6 in production as a budget chip, pricing it at 15-25 percent less than a K6-2 at the same clock speed. The K6-2 competed with the Pentium II, leaving the K6 to compete with Intel’s Celeron.
The K6-2 kept AMD in the game. But it was really the Athlon that let AMD give Intel a serious challenge at the high end of the market.
David Farquhar is a computer security professional, entrepreneur, and author. He has written professionally about computers since 1991, so he was writing about retro computers when they were still new. He has been working in IT professionally since 1994 and has specialized in vulnerability management since 2013. He holds Security+ and CISSP certifications. Today he blogs five times a week, mostly about retro computers and retro gaming covering the time period from 1975 to 2000.