X86-Secret : ES Zone
Nx586-66 ES  (Week 30, Year 1994)   
Nx586-XXXX-4.0-CPC-101 N30000HR AAA0865 N45002HR

Without any doubts one of the rarest CPU of this entire ES collection. Back in 1994, NexGen originally planned to release the Nx586 at 60 and 66 MHz. After some delays, the Nx586 was finally launched at 75, 80 and 90 MHz to compete with the Intel Pentium. The latest frequency (90 MHz) was by far the most common. This 66 MHz Nx586 is a pre-launch sample. It was built by IBM in July 1994, 4 weeks before the next older known Nx586. Its also the only known Nx586 with a frequency below 75 MHz.