The base 478 is a processor socket for Pentium 4 and Mobile Pentium 4 processors and the Pentium 4 -based Celeron and Celeron D processors from Intel.
The Socket 478 replaced the short-lived Socket 423 Pentium 4 of the first series and was replaced by 775 from 2004, Intel's first socket in land-grid - array technology. The unit is called PGA478 in Intel data sheets Socket P has only optical, but no electrical commonality with the Socket 478
When the processor socket 478 cooler is not fixed from the base itself, but by a so-called retention module on the motherboard. These motherboards have holes that span a rectangle of 60 × 76 mm, in which the retention module can engage. This measure was necessary because the cooling of processors has been accomplished with ever larger heat sinks, which gradually got their higher mass not secure grip more about the plastic tabs on the socket.