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Socket J (LGA 771)

Release date	May 16, 2006; 20 years ago (2006-05-16)
Designed by	Intel
Manufactured by	Intel
Type	Land Grid Array (LGA)
Chip form factors	Flip chip land grid array
Contacts	771
FSB protocol	AGTL+
FSB frequency	667 MT/s, 1066 MT/s, 1333 MT/s, 1600 MT/s
Voltage range	Varies (1,3625V max)
Processor dimensions	37.5 × 37.5 mm
Processors	Intel Celeron 445 Intel Core 2 Duo E6x05 Intel Dual-Core Xeon E/X/L 50xx–52xx Intel Quad-Core Xeon X 33xx Intel Quad-Core Xeon E/X/L 53xx–54xx Intel Core 2 Extreme QX9775
Predecessor	Socket 604
Variant	LGA 775 (Socket T)
Successor	LGA 1366
Memory support	DDR2, DDR3
This article is part of the CPU socket series

LGA 771, also known as Socket J, is a CPU interface introduced by Intel in 2006.^[1] It is used in Intel Core microarchitecture and NetBurst microarchitecture (Dempsey) based DP-capable server processors, the Dual-Core Xeon is codenamed Dempsey, Woodcrest, and Wolfdale and the Quad-Core processors Clovertown, Harpertown, and Yorkfield-CL. It is also used for the Core 2 Extreme QX9775, and blade servers designated under Conroe-CL.

It was succeeded by LGA 1366 for the Nehalem-based Xeon processors.

Technical specifications

As its name implies, it is a land grid array with 771 contacts. The socket has 771 protruding spring-loaded pins which touch the lands on the underside of the microprocessor.

The "J" in "Socket J" refers to the now-canceled processor codenamed "Jayhawk", which was expected to debut alongside this interface. It is intended as a successor to Socket 604 and takes much of its design from LGA 775 and is almost pin compatible with LGA 775.

Compared to LGA 775 CPUs, LGA 771 CPUs are rotated 90 degrees and have two pins swapped. Small adapters developed by Chinese computer DIY enthusiasts are available to allow LGA 771 CPUs to be installed in LGA 775 motherboards, if the BIOS microcode supports them (but it is also possible to add supporting microcode manually).^[2] This also allows for overclocking of Xeon (LGA 771) processors when used in the correct (LGA 775) motherboards. Some overclockers have managed quite substantial overclocks such as 4.023GHz on a Xeon X5492 for a total overclock of just over 18%.^[3]

Single core processors

Dual core processors

• Hyper-threading supported only on 50xx series processors(codenamed Dempsey)

Quad core processors

See also

• List of Intel microprocessors
• List of Intel Xeon microprocessors

References