Socket 478 central processing units (CPUs) are any CPU units used in a socket 478 CPU connector. These connectors establish a connection between certain CPUs and the motherboard, allowing the CPU to work on necessary functions. Created by Intel in 2001, the 478 connector is used extensively in two CPU platforms: Pentium 4 and Celeron. Socket 478 CPU units have a processing speed between 1.4 gigahertz (GHz) and 3.46 GHz, and the connector’s front side bus (FSB) is between 400 megahertz (MHz) and 1,066 MHz. These CPUs were phased out in 2008 in favor of socket 775 CPUs.
All CPUs are made to work with a certain type of socket. The socket is made to function with CPUs of a certain speed, measured in either MHz or GHz, and other CPUs will not work and will not fit the socket properly. Intel made the socket 478 to replace the socket 423. The largest difference, beyond having a higher memory threshold, is that the distance between the pins, where the CPU pins fit in, is half that of the socket 423. This allows the socket and CPU to be smaller while having more processing power, resulting in a CPU at 1.38 inches (3.5 centimeters) squared.
Most sockets and their CPU counterparts are made for only one or two CPU types, though they sometimes accommodate more. The socket 478 CPU market was limited to two CPUs, the Pentium 4 and Celeron, the former being used on the higher end and the latter being used for lower processing requirements and cheaper computers. The Celeron model of CPUs worked toward the socket 478’s lower threshold of around 1.5 GHz to 2.5 GHz, while the Pentium 4 was around 2.4 GHz to 3.4 GHz.
The socket 478 CPU FSB clocked in within a range of 400 MHz to 1,066 MHz. The FSB is one of the largest determining factors in how quickly the CPU can work, because the FSB is the unit that bridges the CPU to the main memory. A higher FSB means more calculations and functions can be completed in a second. Just as with the processing speed, Celeron clocks in at the lower end of this spectrum, while Pentium 4 is at the higher end.
Socket 478 CPU units were among the last to use the pin grid array (PGA); the socket 775 that replaced the 478 used a new array known as the land grid array (LGA). This type of arrangement uses flat connectors instead of pins and pinholes. The LGA arrangement creates less heat and allowed better integration than the socket 478 PGA.