PC133

PC133, or PC-133, is a memory speed designation for SDRAM used in desktop personal computers during the late 1990s and early 2000s. It refers to the 133 MHz synchronous DRAM standard and is part of the PC memory speed family (including PC66 and PC100) defined under JEDEC guidelines. The term is commonly used to describe the memory modules and the compatible motherboards from that era.

Technical characteristics of PC133 SDRAM include a 64-bit data path and a 168-pin DIMM form factor. Modules typically operated around 3.3 volts, with some low-voltage variants existing in later implementations. Theoretical bandwidth is about 1066 MB/s (roughly 1.07 GB/s), calculated from 133 MHz clock cycles and an 8-byte data transfer per cycle. As with other SDRAM, data transfers occur in sync with the memory bus.

PC133 was widely used in a range of desktop systems, including Intel Pentium II/III platforms and various AMD configurations, alongside contemporary PC100 systems. Motherboards and memory controllers from that era often supported both speeds, sometimes running modules at a reduced PC100 speed if the system did not enable full PC133 operation. ECC variants andregistered modules were available for servers and workstations, though unbuffered PC133 DIMMs were the more common consumer option.

In the transition to newer technology, PC133 was gradually superseded by DDR SDRAM. DDR memory (often marketed as PC2100/PC2700 and newer) offered higher bandwidth and efficiency, leading to the obsolescence of PC133 in mainstream systems by the mid to late 2000s. Today, PC133 is mostly of historical interest and is used in vintage computer collections or for repair of older hardware.