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Identical to this AMD K5 PR166. This particular model has been manufactured in week 29 of 1997.

In practical terms the K5 PR166 was AMD's top of the line CPU. There are a few PR200 models on the market but they are very rare. AMD didn't want the K5 PR200 to compete with their own AMD K6-line so they quickly stopped production of the PR200.

All in all the AMD K5 didn't sell very well. In European games magazines (at least German, Dutch and British) you can find a few adverts of companies selling systems. Often they only mention the Intel Pentium and sometimes a Cyrix as alternative. The AMD K5 didn't get much notion and if it did it would be the very low end solution: for example an advert with K5-PR100, Cyrix PR166+ and Pentium 133 through 200. > Read more

Same as the K5 PR133 but 16MHz faster.

The K5 PR166 is the second fastest AMD K5. AMD manufactured very few PR200-models but quickly stopped to avoid creating a situation in which the K5-PR200 would compete with AMD's own, and then new, AMD K6.

All in all the AMD K5 wasn't popular. It was late to market, expensive to produce and had plenty of competition by Cyrix and Intel. Performance-wise the K5 runs well if you rely on integer calculations. The K5's floating point unit is weak compared to the Intel Pentium so you'd better not try playing Quake on these . Doom, however, runs great! > Read more

This is the second generation AMD K5 (with the 5k86 core instead of SSA/5). It has been optimized and the branch-predictor has been enabled so it should be faster per MHz than the original one. Because of this AMD used the PR number (Performance Rating) to indicate performance. The original AMD K5 PR75, PR90 and PR100 ran at respectively 75MHz, 90MHz and 100MHz. This K5 PR133 works at just 100MHz and the PR166 at 116MHz.

In terms of performance the PR-rating is comparable to it's competitors if the CPU has to calculate integers. See how Dhrystone and Doom runs quite well, but Quake and DOSBench (DOSBench is FPU dependant) show another face of the K5: really slow with floating-point calculations. AMD was no exception in this; Cyrix 6x86 and IDT WinChip also had weak FPU's.

In terms of clock-for-clock performance (i.e. how much can a CPU do per MHz) the K5 is fairly good. The PR133 runs at 100MHz and with Doom it runs equal to the Pentium 133 and 150. Again with FPU it's a different story.

Don't confuse the 5k86 core with the name of the AMD 5k86 P75 which is just an older AMD SSA/5 core but with a different name attached to the CPU. > Read more