The Intel Pentium III 866 was a desktop processor with 1 core, launched in June 2001. It is part of the Pentium III lineup, using the Coppermine T architecture with Socket 370. Pentium III 866 has 256 KB of L2 cache and operates at 866 MHz. Intel is making the Pentium III 866 on a 180 nm production node using 44 million transistors. The multiplier is locked on Pentium III 866, which limits its overclocking potential.
With a TDP of 38 W, the Pentium III 866 consumes only little energy. Although the processor doesn't come with integrated graphics, certain motherboards with compatible chipsets can provide this capability.
Many games will refuse to start on this processor due to the lack of the SSE2/SSE3/SSE4 instruction set.