Socket 478 is a central processing unit (CPU), or microprocessor, socket that contains 478 pins. Its purpose is to provide physical support for the processor, and to electrically connect it with the motherboard of a personal computer (PC). The Socket 478, like other components of its ilk, allows users to plug in or remove CPUs safely. It adopts the pin grid array (PGA) design, which means that its 478 pins are uniformly arranged within its square-like structure. Introduced in 2002, Intel relied on the Socket 478 for several of its CPUs until 2006, when it began to phase it out in favor of the LGA 775.
When semiconductor manufacturer Advanced Micro Devices (AMD) released its 462-pin Socket A for its Thunderbird-codenamed Athlon microprocessors that debuted in June 2000, its main competitor, Intel Corporation, needed a socket to rival theirs. AMD was handily beating Intel with the Athlon's third generation of production, which it nicknamed "XP." In response, Intel came out with a CPU socket that superseded the Socket A with 16 more pins.
Intel originated Socket 478 for the then-flagship Intel Pentium 4 chips codenamed Northwood, which it released in January 2002. The socket supported a Northwood processing range of 1.4 to 3.4 gigahertz. It also supported the budget-oriented Intel Celeron chips that were based on the Northwood microarchitecture, with a processing speed range of 1.7 to 2.8 GHz. Later CPUs that Intel produced for compatibility with Socket 478 included the Prescott Intel Pentium 4, which are smaller than their older Northwood siblings; and the Celeron D, which were actually the last processors made for the socket. Regardless of computer chip brand, Socket 478 supports data transfer speeds of 400, 533 and 800 million transfers per second, which translates into 400, 533 and 800 megahertz, respectively.
Each Socket 478 measures 1.38 square inches (8.90 square centimeters). The socket belongs to a subcategory of PGA design called flip-chip pin grid array (FC-PGA or FCPGA). This means that the silicone core, as the hottest part of the processor, is facing upward, thus avoiding contact with the computer's motherboard. This allows the user to introduce a heatsink, which draws away heat from the CPU to avoid overheating and consequent malfunction. Users, however, must make sure that they adhere to Intel's mechanical maximum load limits, which consist of a dynamic force of 890 newtons (200 pounds-force), static force of 445 newtons (100 pounds-force) and transient force of 667 newtons (150 pounds-force).