Intel Pentium II introduced May 7, 1997

Last Updated on April 15, 2026 by Dave Farquhar

28 years ago, on May 7, 1997, Intel introduced its Pentium II processor. It wasn’t the first followup to the very successful Pentium. But the Pentium II overcame problems with the Pentium Pro that kept it from gaining more widespread mainstream acceptance.

Intel Pentium II vs Pentium Pro

The Pentium Pro was a great CPU with one fatal flaw. It ran 16-bit code more slowly than a Pentium, or, at best, at Pentium-like speeds, while costing considerably more. To get around this, Intel moved the Pentium II to a cartridge design. The cartridge plugged into a slot in the motherboard instead of a socket. Intel called the connector Slot 1.

Using a cartridge allowed Intel to move the cache off the CPU die and ramp up clock speeds. This actually made the CPU even slower clock for clock, but doubling the L1 and L2 cache sizes and being able reach core clock speeds of up to 300 MHz compensated for that. Intel also added segment register caches to improve 16-bit performance.

By adding MMX, making the other changes, and ramping up clock speeds, the Pentium II ended up being a very successful CPU. It ran Windows 95 and 98 rather well and sold at mainstream price points. Intel later increased the bus speed to 100 MHz from 66 MHz, and reached a maximum clock rate of 450 MHz with this generation.

In February 1999, Intel introduced the very similar Pentium III, which only added the then-new SSE instruction set to the Pentium II. The Pentium III eventually replaced the Pentium II entirely. Intel continued Pentium II production until June 2001 for desktop units, September 2001 for mobile units, and the end of 2003 for embedded devices.

Pentium II variants

The first-generation Pentium II, code named Klamath, was produced in a 0.35 ?m process and ran at 233, 266, or 300 MHz. Intel initially priced it at $636, $775, and $1,981, respectively, in qualtities of 1,000 units, according to the May 12, 1997 issue of Infoworld. You paid dearly for that last 33 MHz. PCs containing these CPUs sold for $3,500 to $5,000, according to the January 6, 1998 issue of PC Magazine.

Deschutes, introduced in January 1998, was produced in a 0.25 ?m process. This decreased the power draw and increased the minimum clock speed to 333 MHz. The process shrink also decreased cost, allowing the 333 MHz version to sell for $722 in quantities of 1,000, acccording to the January 26, 1998 issue of Infoworld. In April 1998, Intel added two new models, running at a 100 MHz bus speed, with core clock rates of 350 and 400 MHz, priced at $621 and $824. A 450 MHz model followed in August, initially priced at $669.

Pricing pressure from AMD’s K6 forced Intel to lower prices pretty aggressively, with the cost of the flagship Pentium II dropping from $1,981 for a 300 MHz model in May 1997 to $669 for a 450 MHz model in August 1998. Purchasers got 50% more clock speed for 1/3 the price after 15 months. When that wasn’t enough, Intel created its low-end Celeron, with was a Pentium II core with no L2 cache, and later with 128K of L2 cache.

Although in May 1997, Anandtech expected the Pentium II to reach clock speeds of up to 600 MHz, Intel never officially released anything faster than 450 MHz, saving the higher clock rates for the Pentium III generation.

Use as a retro PC

The Pentium II isn’t as popular as a retro PC today as it was as a mainstream CPU in the late 90s. That’s because it’s not as versatile as a Pentium MMX, which can be downclocked to reach 486 or even 386-level performance. For running late 90s software, a Pentium III or AMD Athlon will do even better, since they can reach much higher clock speeds. At 800 MHz, either a P3 or Athlon can exceed 60 frames per second in Quake at 640×480, while a Pentium II at 450 MHz  gets just over 40 frames per second.

But if you want to run even higher resolutions, a Pentium 4 reaches still-higher frame rates, and a Pentium 4 is likely to be easier to find.

A Pentium II has its uses, but its relatively short lifespan kept it from reaching the same status as the 486DX2 and original Pentium did.

Dave Farquhar

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.