Socket 478
Processor socket made by Intel

Socket 478, also known as mPGA478 or mPGA478B, is a 478-contact CPU socket used for Intel's Pentium 4 and Celeron series CPUs.
Socket 478 was launched in August 2001 in advance of the Northwood core to compete with AMD's 462-pin Socket A and their Athlon XP processors. Socket 478 was intended to be the replacement for Socket 423, a Willamette-based processor socket which was on the market for only a short time.
This was the last Intel desktop socket to use a pin grid array (PGA) interface. All later Intel desktop sockets use a land grid array (LGA) interface.
Socket 478 marked the beginning of Intel 64 and NX bit with support on some later processors. Intel discontinued Socket 478 in favor of LGA 775 with the launch of the 64-bit version of its 90 nm "Prescott"-based Pentium 4 HT and Celeron D in 2004.
01Technical specifications
Socket 478 was used for all Northwood Pentium 4 and Celeron processors. It supported the first Prescott Pentium 4 processors and all Willamette Celerons, along with several of the Willamette-series Pentium 4s. Socket 478 also supported the newer Prescott-based Celeron D processors (which were also one of the last CPUs made for the socket), and early Pentium 4 Extreme Edition processors with 2 MB of L3 CPU cache.
While Intel's mobile CPUs are available in 478-pin packages, they in fact only operate in a range of slightly differing sockets such as Socket 479 (both mPGA478A and mPGA478C/mPGA479M/μFCPGA/μPGA479M), Socket M, and Socket P, all of which are electrically (and sometimes pin) incompatible with each other including Socket 478.
Socket 478 is used in combination with DDR SDRAM, as well as SDR SDRAM, RDRAM and DDR2 SDRAM.

02Heatsink
The 4 holes for fastening the heatsink to the motherboard are placed in a rectangle with lateral lengths of 60 mm and 75 mm.
03Mechanical load limits
All sockets (Pentium 4 and Celeron) have the following mechanical maximum load limits which should not be exceeded during heatsink assembly, shipping conditions, or standard use. Load above those limits may crack the processor die and make it unusable. The limits are included in the table below.
Sources and credits
This article is adapted from the Wikipedia article “Socket 478”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- Socket PGA478B.jpg by JulianVilla26, CC BY-SA 4.0
- Pentium 4 - SL5TK - pin side-3057.jpg by Raimond Spekking, CC BY-SA 4.0
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