X86-Secret : ES Zone
Pentium III 400B MHz ES  (Week 46, Year 1998)   
Intel Confidential Q855ES / 48469419-0343 A4 / i'98 80525PZ400512

Here is a really rare engineering sample. At first sight, it looked like a Pentium III (80525) in a SECC 2 cartridge, clocked at 400 MHz (400) and with 512 Kb of L2 cache. However, this CPU have a strange particularity : It was designed only to test the new FSB133 platform (Motherboard and chipset). Thus, like you can see on marking, it was designed to work at 400 MHz with 3*133 MHz ! The FSB133 (PZ on the marking) was introduced some months after. All 450/500 MHz Pentium III was clocked with a 100 MHz FSB