Chip collector showcases 'rarest x86 CPU' in their hoard — Rise mP6 266 ticked along at 200MHz in 1998

Some images demonstrating one of the rarest x86 CPUs still running have been shared online. We thank CPU collector and silicon lover, konkretor, for this particular retro tech flashback. However, it is probably fair to say that the highlighted Rise mP6 266 wins more points for obscurity than nostalgia. Though already a keen PC builder and tinkerer in 1998, I don’t recall seeing, hearing, or reading anything about this Super Socket 7 and MMX instruction set compatible processor at the time.

The main image shows the Rise mP6 266 CPU physically installed on an Asus P5A-B Super Socket 7 motherboard. This Asus board featured the ALi Aladdin V chipset and was a viable platform for the exceptionally broad range of x86 CPU manufacturers there were around at the time. Socket 7 CPUs from Intel (Pentium MMX), AMD (k6, K6-2), Cyrix (MII), and IDT WinChip were all happy to be paired with this AGP2X, 3x PCI, 2x ISA slot motherboard, which also supported overclocking.

Another image from konkretor actually shows the Rise mP6 CPU stats as shown in CPU-Z. This confirms the chip was indeed a Socket 7-compatible one, with a core voltage of 2.832V. Despite the high voltage, by today’s standards, the clock speeds and modest TDP (8.54W) meant passive cooling was usually sufficient during this era.

You may be wondering about the discrepancy between the Rise mP6 266 CPU’s name and the 200 MHz frequency reported by CPU-Z. This reflects an industry naming trend of the era, where chips from Intel rivals were sold with a P-rating, or Pentium-rating, number attached. AMD and Cyrix would also (in)famously use this scheme. In the case of the Rise mP6 266, buyers would be asked to believe that this 200 MHz chip performed on a par with a 266 MHz Intel Pentium…

Rise and fall

We reached out to konkretor about the provenance of their Rise mP6 266 CPU. The story was sadly unglamorous, with the CPU collector admitting the chip was bought “a few years ago from a China eBay account, new old stock, that was the whole story, no special.”

For some further background information about the TSMC-fabbed 250nm Rise mP6 266 CPU, there are few resources, but thankfully, a PDF copy of the processor data sheet for its 333 and 366 MHz brethren can still be found online, as well as a few notes about the short-lived CPU family on Wikipedia.

Precipitated from five years of development, Rise, and its mP6 line, quietly fizzled out before the year 2000 arrived. This will surely have contributed to its scarcity on the used market today, and its purported “rarest x86 CPU” status suggested by konkretor.

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