Intel Pentium II SL2S5 333MHz Slot 1 CPU Processor 80523PX333512 MMX

Intel Pentium II SL2S5 333MHz Slot 1 CPU Processor 80523PX333512 MMX

The Intel Pentium II SL2S5 is a 333MHz sixth-generation x86 processor in Intel's Single Edge Contact Cartridge (SECC) format, designed for Slot 1 motherboards. It carries the OEM part number 80523PX333512, stepping code SL2S5, and includes Intel's MMX multimedia instruction set extensions. This is the Klamath-core Pentium II variant running on a 66MHz front-side bus with 512KB of half-speed L2 cache integrated into the cartridge module.

Specifications & What's Included

• Brand: Intel
• Product Family: Pentium II (Klamath core)
• OPN / Part Number: 80523PX333512
• S-Spec / Stepping: SL2S5
• Clock Speed: 333 MHz
• Front-Side Bus (FSB): 66 MHz
• L2 Cache: 512 KB (on-cartridge, running at half core speed)
• Socket / Interface: Slot 1 (SECC — Single Edge Contact Cartridge)
• Instruction Set: MMX
• Country of Manufacture: Malaysia (per side label)
• Compatible chipsets: Intel 440LX, 440BX, 440EX
• Includes: CPU cartridge only — no heatsink, fan, or retention mechanism included

Applications

The Pentium II was Intel's mainstream desktop and workstation processor from 1997 through roughly 1999, replacing the Pentium Pro and original Pentium MMX lines. The 333MHz speed grade was one of the faster Slot 1 parts of the Klamath generation and was used widely in business desktops, entry-level workstations, and performance home PCs of the era. Compatible motherboards include those built around Intel's 440LX and 440BX chipsets — the 440BX in particular became one of the most respected PC chipsets of the late 1990s and supported overclocking the 333MHz part to 400MHz+ on a 100MHz FSB. The Pentium II platform is well-documented in retro computing and vintage PC restoration communities, and working examples remain sought after for period-correct builds, legacy software environments, and late-1990s PC museum projects. The SECC cartridge form factor was unique to this processor generation; it houses the processor die and L2 cache chips on a small PCB enclosed in a plastic shell that snaps into the Slot 1 retention mechanism on the motherboard.