The original Xbox's Pentium III-based CPU had a clock speed of 733 MHz.
Microsoft designed the console with a customized Intel Coppermine-based processor. Its 733 MHz clock speed was unusually high for a dedicated game console of its 2001 generation, helping the system handle the demanding 3D graphics and online features planned for Xbox.
The CPU was paired with a custom NVIDIA graphics processor, 64 MB of unified DDR SDRAM, and an internal hard disk. These components gave the Xbox a PC-like architecture while keeping the hardware fixed for developers.
The 733 MHz figure describes the processor's clock speed, not the console's graphics performance or memory speed. It is also separate from the later Xbox 360, which used a three-core PowerPC-based processor.