Socket 423 / Socket PGA423

Socket 423, also called PGA423, is a Pin Grid Array (PGA) socket introduced together with Pentium 4 microprocessor family in November 2000. The socket supported only Pentium 4 CPUs with Willamette core and was replaced with socket 478 just in 9 months after its introduction.

The size of PGA423 socket is 2.1" x 2.1" (5.33 cm x 5.33 cm). The socket has 423 pin holes arranged as 39 x 39 matrix with 26 x 26 section of pins removed. No corner pins in the socket are plugged, but, because the 26 x 26 section is removed not exactly from the center of the pin grid, there is only one way to insert the CPU into the socket.

Supported processors

Desktop Pentium 4 Willamette (1.3 GHz - 2.0 GHz). The fastest socket 423 CPU is Pentium 4 2.0 GHz. The socket may support faster socket 478 Pentium 4 processors when a special socket 423 to socket 478 adapter is used. Please see "Upgrading socket 423 motherboards" section below for more information.

There are no CPUs from other manufacturers compatible with socket PGA423.

Compatible package types

423-pin package - bottom view

Organic Land Grid Array package with Integrated Heat Spreader (IHS) on 423-pin interposer.

The picture on the right shows the bottom view of the 423-pin package that fits into the Socket 423.

Upgrading socket 423 motherboards

To determine the fastest processor for your motherboard you'll need to:

  • Determine manufacturer and model of your motherboard,
  • Search on manufacturer's website for the motherboard model.

In most cases the fastest CPU for socket 423 motherboard will be Pentium 4 2.0 GHz. For upgrade information for ASUS, ECS, DFI, Gigabyte Technology, Jetway, MSI and PC Chips motherboards please check CPU-Upgrade motherboard database.

It is possible to use socket 478 Pentium 4 CPUs with Northwood core in socket 423 motherboards with the help of special CPU upgrade adapters, such as Powerleap PL-P4/N or Upgradeware Technology p478. These adapters plug into socket 423 and have a socket 478 on the top. At the very least the adapters can be used to upgrade to Pentium 4 2.6 GHz or Pentium 4 2.8 GHz with 400 MHz FSB. Motherboards supporting 533 MHz FSB can be upgraded to even faster Pentium 4 processors.

Processor Installation

For processor installation instructions please look at your motherboard manual, or go to this page on Intel website (scroll down to "Processor Installation" section).


S423 to S478 adapter

2010-04-26 03:16:04
Posted by: HOMEBOY87

Just for the records:
i've got a S423 to S478 adapter. bought it on ebay for my Asus P4T.

it *only* works with Willamette S478 Pentium 4 CPUs.
With a Northwood P4, it does not even POST.
Tried it with a 1.8GHz Northwood P4 and a 2.4GHz Northwood P4 (both with 400MHz FSB).
No POST.. nothing.
A 1.6GHz Willamette S478 P4 works though.

Pretty disappointing :o(

S423 to S478 adapter


2012-01-30 10:36:36
Posted by: \axel_as

same here, only willamete supporting.

Last modified: 10 Mar 2014
Terms and Conditions · Privacy Policy · Contact Us (c) Copyright 2003 - 2010 Gennadiy Shvets

Search CPU-World

Search site contents:

Identify part

Identify CPU, FPU or MCU:

Quick Links

Jump to CPU / Family

Type in partial CPU manufacturer, family, model and/or number.