The VIA C3 was originally known as the VIA Cyrix III and was designed to fit into the same Socket 370 used by the Pentium III and Celeron III. The initial versions of the C3, code named Joshua and Samuel, had 128KB L1 cache but didn't contain any L2 cache.

As a consequence, they had much lower performance than similar 500MHz-class processors. The original Cyrix III/C3, code named Joshua, was developed by former Cyrix engineers after VIA bought Cyrix in late 1998, but the Samuel and subsequent versions are based on the Centaur Winchip (VIA purchased Centaur in 1999).

The Samuel was built with a .18-micron process, whereas the Samuel 2 is a development of the Samuel with 64KB of L2 cache on board and is built on a .15-micron process. The Ezra core was the first .13-micron process C3 processor, but it, like previous C3 processors, was not compatible with Tualatin (late Pentium III-compatible) motherboards.

The Ezra-T core was the first C3 to reach 1GHz and the first to support Tualatin motherboards. The latest C3 uses the Nehemiah core and features clock speeds over 1GHz and built-in encryption. C3 models feature 100MHz FSB (750MHz and 900MHz models) or 133MHz FSP (733MHz, 800MHz, 866MHz, 933MHz, and higher).

The C3 is fully software compatible with other x86 processors, including Pentium III and Celeron, but its microarchitecture is designed to enhance the performance of most frequently used instructions while reducing the performance of seldom-used instructions.

This design feature significantly reduces the die size needed for C3 processors, but it also reduces performance in multimedia and graphics operations. By reducing the die size, the C3 in its Nehemiah version offers typical power consumption of only 11.25 watts, making it the coolest running processor available for Socket 370 applications.

Because of its low power consumption, cool operation, and relatively low performance compared to the Intel Celeron, the C3 processor should be considered primarily for computing appliances, set-top boxes, and portable computers in which small size and low power/cooling requirements (rather than performance) are paramount.

The C3 is also available in an enhanced ball grid array (EBGA) package called the E-series. E-series C3 processors are used for permanent installation on motherboards such as the Mini-ITX ultra-compact form factor designs also produced by VIA.