Pentium MMX retro gaming PC

Last Updated on May 29, 2023 by Dave Farquhar

The Pentium MMX represents a sweet spot in retro computing. Prices aren’t too far out of hand yet, and with one system and a utility, you can slow it down to match speeds with various other vintage systems, including the 386 and 486 generation, for running speed-sensitive games. This means one system can run DOS games going back to approximately 1987 or 1988, and still do relatively well with DOS and Windows games up to approximately 1998.

It also means you can use relatively inexpensive and still-plentiful PCI cards. PCI-based 486s exist but they are uncommon and getting expensive. And 386 PCI motherboards don’t exist.

The secret: SETMUL

Pentium MMX PC
A Pentium MMX PC like this Gateway 2000 desktop from the late 90s makes for a surprisingly versatile retro DOS PC.

A free DOS utility called SETMUL can disable various CPU features that make one generation of CPU faster than the previous one. Disable four features in a Pentium MMX and disable the motherboard cache, and you can slow it down to about the speed of a 40 MHz 386. And with various combinations of features disabled, you can match speeds with various 486 CPUs, optimal for running DOS games dating to approximately 1992 to 1994. Going beyond 1994, you may be able to just run them at full speed. But if you need to tune the speed a bit, disabling 1-2 features gets you into the speed range of early Pentium CPUs.

Phil’s Computer Lab includes a nice chart showing the speeds you can achieve. And if you scroll to the end of his page, you can download a bundle that includes the SETMUL utility and a collection of seven batch files to fine-tune the speeds.

Note that this capability is unique to the Pentium MMX. CPUs from AMD and Cyrix from the same era can be adjusted to a lesser degree, but dialing them into low-end 486 or 386 performance isn’t as feasible.

Using SETMUL to fine-tune Pentium MMX performance

Certain speeds of 486s are hard to dial into, depending on the clock rate you’re running your Pentium MMX. But I’m not too worried about that, as you can approximate a 33 MHz 486 pretty easily, and either a 66 or 100 MHz DX2 or DX4. And there was little, if any software that ran too fast at 100 MHz but just right at 66.

In my case, I was able to get lower-end performance by clocking my Pentium MMX at 100 MHz, using a 50 MHz bus and 2x multiplier on a Socket 7 board with 72-pin SIMMs. Between that and using Phil’s batch files, I was able to dial into 486 DX2-80-like performance at the higher end and 386DX-25-like performance at the low end.

When you need to run a speed-sensitive game, it takes some experimentation, but try the batch file that seems closest to the era of the game you want to play, then run the game. Track which one worked, and maybe write a batch file that runs the appropriate batch file, then runs the game.

There is no perfect DOS gaming PC. But a Pentium MMX plus SETMUL might be as close as you can get. One machine can span the decade of the 1990s, and crucially, prices haven’t gotten out of hand yet.

Advantages of a Pentium MMX for retro computing

If you’re careful, you can pick up a 166 MHz Pentium MMX CPU for around $10. Finding a suitable motherboard is tougher, but still doable. I think it’s a bit easier to find a motherboard with a CPU and memory bundled. Just make sure whatever you buy fits the case you plan to put it in. You’ll want one with an ATX power connector at the very least. You can put an AT form factor board in an ATX case. Be careful of name-brand boards that frequently were LPX or another form factor that won’t work in an ATX case.

Another option is a complete or semi-complete system or a laptop. The price is reasonable, sometimes lower than buying up parts and building it yourself. You can pick up a Compaq, Dell, HP, or IBM system with a Pentium MMX inside for around $150, even at Ebay prices. If you’re patient, you can find one at a garage or estate sale. You’ll just have to balance the value of your time, whether going to sales is something you enjoy or not, and your travel costs. Locating a model from your favorite 90s computer brand and matching peripherals can be a fun challenge.

It saves money and space, since one system can run software from the 386, 486, and Pentium eras while looking the part of a vintage rig. Load Windows 98 on a compact flash card to run Pentium-era stuff, and load DOS on another compact flash card with the suite from Phil’s Computer Lab I linked above to run 386- and 486-era stuff.

Pentium MMX era peripherals

Pentium MMX 233 MHz CPU
Intel sold the Pentium MMX CPU for about four years.

Another advantage of this era is that the peripherals are still affordable, not just the CPU. They use PS/2 keyboards, still readily available at thrift stores. LCD monitors started getting affordable while these machines were still viable. So you can use an LCD monitor with them without it looking wrong. I can attest I connected LCD monitors to Pentium MMX systems in the early 2000s.

PCI video cards, network cards, and the like are still affordable. IDE 40-pin hard drives are still affordable. Compact flash adapters and compact flash cards are even more affordable as an alternative to an IDE drive. A 40-pin IDE DVD-ROM drive looks the part in these systems and is still affordable too. Sound Blaster cards from this era aren’t terribly expensive, and you can get away with an Aztech card. An Aztech is cheaper and, arguably, better than a Sound Blaster 16.

The most expensive part from this era is a Voodoo 2 video card, if you want to get into high-end late 90s 3D gaming. But that component is purely optional.

Pentium MMX CPU

IBM Pentium MMX system
You can get a Pentium MMX system from your favorite 90s brand. It runs DOS and Windows 98 well and looks the part. Chasing down matching peripherals presents a fun and inexpensive challenge. And the CRT is optional. Some people upgraded to LCDs during this era of PC.

Intel introduced the Pentium MMX CPU in October 1996, and sold them through October 2000. It provided a modest upgrade over the original Pentium architecture, adding 57 new multimedia-oriented MMX instructions and 32K of L1 cache, vs 16K on the earlier Pentiums. The most common clock speeds were 166, 200, and 233 MHz. It ran on a dual 2.8 volt core /3.3 volt I/O voltage that wasn’t compatible with earlier Pentiums, although it used the same Socket 7 pinout. Intel briefly marketed a Pentium MMX Overdrive upgrade for earlier Pentium systems.

The Pentium MMX contained 4.5 million transistors and had an area of 140 square millimeters. It was fabricated in a 0.28 µm CMOS process with the same metal pitches as the previous 0.35 µm BiCMOS process. Intel described it as “0.35 µm” because of its similar transistor density.

Like the earlier Pentiums, Pentium MMX CPUs needed active cooling. A CPU/heatsink combination compatible with other Socket 7 processors works fine with a Pentium MMX.

Intel’s Pentium II quickly followed in May 1997, and the Pentium Pro preceded it in November 1995, so the Pentium MMX was never Intel’s top-end architecture. It was always more of a midrange/value CPU, but represented the mainstream for about two years. It was also similar enough to the earlier Pentium to give it a lot of versatility when it comes to running 1990s software.

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5 thoughts on “Pentium MMX retro gaming PC

  • May 8, 2023 at 8:59 am

    It’s a worthwhile quest, finding one Retro PC to cover the entire decade of the 1990s. I’ve used Pentium MMX at 200 and 233MHz with good success. However, I don’t really find any games post-1980’s that don’t know how to slow themselves down on faster CPUs. I’m curious are there some popular games that required this? Wing Commander is the only one I know of…

    • May 8, 2023 at 8:56 pm

      Wing Commander is the big-name one. There was a game called Tank Wars, I can’t remember if it was freeware or shareware, but it was a traditional artillery game where you specify angles and power and try to blow each other up. My friends and I played it a ton in the 486 era. It was unplayable on a Pentium, but I remember playing it on anything ranging from 386 machines to a 50 MHz 486DX2. Was Tank Wars popular? Who knows, but my friends missed it after we all retired our 486s.

      • May 17, 2023 at 9:28 am

        Hi. Maybe you are referring to “Scorched Earth”? I also played a lot of that around 1995 while underway on a submarine… I need to find a copy and see how it runs on my Pentium.

  • May 8, 2023 at 9:34 am

    Always a nice read.
    Do you remember a good LCD that goes with a retro MMX-era pc?

    • May 8, 2023 at 9:00 pm

      Thanks, as always! Just my opinion, but you can’t go wrong with a beige NEC Multisync LCD. That’s what I was deploying around the year 2000. An IBM 4820 LCD intended for their POS systems would look the part too, if you get a beige one. A fair number of those are still available on the secondhand market.


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