You may have read too much into my comment. Your results are certainly of interest for benchmarking and charting purposes, which for some people, is all they care about. Other members are interested in building both a fast and solid system. I am interested in both, but ultimately, I like my systems to be stable and give most credit to benchmarks for stable systems. The AMD X5-200 charted in the Ultimate 486 Benchmark Comparison was surprisingly stable.

I only have an AMD X5-200 benched at 50x4. Your 3x66 and 3x60 systems have surprisingly fast memory throughput. For charting purposes, I would need to have the results from all the programs listed on the Ultimate 486 Benchmark Comparison to add your values to the chart. It sounds like you may be able to do this at 3x60 and I would be interested to see the results. It also sounds like you may be able to get a system stable at 60x3 and may be something you want to pursue. Could you also show the Cachechk -v7 results? cachechk.exe -d -t4 would be sufficient.

Your Speedsys averaged memory throughput is as fast as my L2 cache throughput at 2x66, making your system not really need L2 cache. This is why it would be of interest to demonstrate your system stable at 3x60.

Anonymous Coward wrote:

I never understood why no company ever released a 486 to Pentium upgrade adapter (the shitty one from Intel doesn't count). We had these things for 8088s, 286s, and 386s called "dinguses". Was there something so different about Pentium that made a socket adapter too difficult to produce?
Ideally what I'd want though is a newly fabricated 486 CPU that had really high multipliers but bus speeds of 33 and 40MHz.

I have seen 2rd party 486s with added float point operations.

Could you provide any details on these "2nd party" 486s?

haha 🤣 "2rd" woops. Unfortunately I'm just a crazy guy talking out of his arse as i do not have a source I just remember stumbling on to a web page with list of the 3rd party 486s made through the years, and then seeing how expensive they were on eBay.

I just had a thought, since it's looking like running beyond 200MHz is slim... has anyone had any success running at a 66MHz bus w/ 1/2 PCI divider? Even 66MHz x 2? Which RAM and cache are you using to achieve a stable 66MHz bus?

AMD x5-133's only have 3x and 4x operation, so personally I cannot test a 66MHz x 2, but for these chips what about 66MHz x 3?

A 200MHz AMD x5, 66MHz bus, 33MHz PCI clock sounds mighty promising. Finding the right combination of RAM and cache seems to be the tough part.

It is too difficult to find an AMD X5 that is stable at 200 MHz. I've stopped looking for these magic chips.

The only 486 chip I've seen relatively stable at 66 Mhz x 2 was an IBM 5x86c. Maybe there is some pin modification you can do to get the X2 into 2x mode? You can also try using an AM486DX4-120 to run at 2x66. You loose out on 8 KB of L1 cache though. The Intel DX4-100 will also run at 2x66, but it is not very stable.

pushing over 200mhz seems crazy for me, as 486 components are getting rare today, its better to run them within a safe limit rather than risk blowing up.

numeriK wrote:

While I can respect where you're coming from, I disagree. A benchmark is exactly that. Many of the best 3DMark systems in the […]
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For my interests, the benchmark results are not of interest until the system is demonstrated stable.

While I can respect where you're coming from, I disagree. A benchmark is exactly that. Many of the best 3DMark systems in the world are only stable long enough to run 3DMark, usually due to thermal issues/lack of enough liquid nitrogen. So, according to you my results are not valid?

What I'm testing here is the limits of a 486. Benchmark results prove these limits can be achieved, for a short period of time or not. I'm not looking for a 200Mhz+ 486 that's 100% 24/7 stable - to be quite honest that's most likely impossible - but who truely knows? Thus the point of this thread.

I'm playing with 60-66Mhz bus speeds and ~205Mhz CPU speeds, and I'm getting complete runs through various benchmarks, yet they're irrelevant?

Like I said, I can appreciate where you're coming from but that simply isn't the point of this thread. If I want a 100% stable system I'll go back to factory defaults... 😵

The point that is being made that the system might run through your benchmarks OK, but may fail as soon as you try booting a game or other app. It may also fail to boot Windows or do undesirable things when writing information to memory or to your hard drive leading to data corruption. A system that is only good for running benchmarks isn't worth the effort that went into building it because you'll never be able to use it for anything else.