The CPU in the Xbox was a custom Pentium III running at 733MHz. The 'custom' part of this was that that the Pentium III in the Xbox was that it had only 128KB L2 cache instead of the usual 256KB. This allowed Microsoft to buy them at a bit of a discount and Intel to shift a few more CPUs.
- Mobile Intel® Celeron® Processor (0.18μ) in BGA2 and Micro-PGA2 Packages (This datasheet is for the mobile version Coppermine with 256kB L2 cache. It does not contain the Xbox Coppermine-128 with 128kB L2 cache at 733MHz (S-Spec SL5SN). No such datasheet exists. Both differences are pin compatible.
- CPU upgrading adapter for a Microsoft XboxTM game machine US Patent Application 20050282621 by Friendtech, filed 2003-08-21.