X86-Secret : ES Zone
AMD K6-2+ 570 Mhz  (Week 00, Year 2000)   
AMD-K6-2+/570ACZ - 2.0V CORE/3.3V I/O - A 0020DPMW

Even if they were never mentioned in the official AMD website, AMD procuded very few K6-2+ clocked at an awesome 570 Mhz. Targetted for the mobile segment, these CPUs were the highest clocked Socket 7 CPU. They used a 95 MHz system bus with a 6.0x ratio. Standard voltage is 2.0V and overclocking is really easy : We were able to reach an impressive 750 Mhz with air-cooling only and 2.4V !