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Intel Sockets: LGA 775, LGA 1156, LGA 1366, And LGA 1155

Upgrading And Repairing PCs 21st Edition: Processor Features
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Socket LGA 775

Socket LGA 775 (also called Socket T) is used by the Core 2 Duo/Quad processors, the most recent versions of the Intel Pentium 4 Prescott processor and the Pentium D and Pentium Extreme Edition processors. Some versions of the Celeron and Celeron D also use Socket LGA 775. Socket LGA 775, unlike earlier Intel processor sockets, uses a land grid array format, so the pins are on the socket, rather than the processor.

LGA uses gold pads (called lands) on the bottom of the processor to replace the pins used in PGA packages. It allows for much greater clamping forces via a load plate with a locking lever, with greater stability and improved thermal transfer (better cooling). The first LGA processors were the Pentium II and Celeron processors in 1997; in those processors, an LGA chip was soldered on the Slot-1 cartridge. LGA is a recycled version of what was previously called leadless chip carrier (LCC) packaging. This was used way back on the 286 processor in 1984, and it had gold lands around the edge only. (There were far fewer pins back then.) In other ways, LGA is simply a modified version of ball grid array (BGA), with gold lands replacing the solder balls, making it more suitable for socketed (rather than soldered) applications. Socket LGA 775 is shown in the figure below.

Socket LGA775 (Socket T)Socket LGA775 (Socket T)

The release lever on the left raises the load plate out of the way to permit the processor to be placed over the contacts.

Socket LGA 1156

Socket LGA 1156 (also known as Socket H) was introduced in September 2009 and was designed to support Intel Core ix-series processors featuring an integrated chipset northbridge, including a dual-channel DDR3 memory controller and optional integrated graphics. Socket LGA 1156 uses a land grid array format, so the pins are on the socket, rather than the processor. Socket LGA 1156 is shown in the figure below.

Socket LGA1156 (Socket H)Socket LGA1156 (Socket H)

Because the processor includes the chipset northbridge, Socket LGA 1156 is designed to interface between a processor and a Platform Controller Hub (PCH), which is the new name used for the southbridge component in supporting 5x series chipsets. The LGA 1156 interface includes the following:

  • PCI Express x16 v2.0—For connection to either a single PCIe x16 slot, or two PCIe x8 slots supporting video cards.
  • DMI (Direct Media Interface)—For data transfer between the processor and the PCH. DMI in this case is essentially a modified PCI Express x4 v2.0 connection, with a bandwidth of 2 GB/s.
  • DDR3 dual-channel—For direct connection between the memory controller integrated into the processor and DDR3 SDRAM modules in a dual-channel configuration.
  • FDI (Flexible Display Interface)—For the transfer of digital display data between the (optional) processor integrated graphics and the PCH.

When processors with integrated graphics are used, the Flexible Display Interface carries digital display data from the GPU in the processor to the display interface circuitry in the PCH. Depending on the motherboard, the display interface can support DisplayPort, High Definition Multimedia Interface (HDMI), Digital Visual Interface (DVI), or Video Graphics Array (VGA) connectors.

Socket LGA 1366

Socket LGA 1366 (also known as Socket B) was introduced in November 2008 to support high-end Intel Core i7-series processors, including an integrated triple-channel DDR3 memory controller, but which also requires an external chipset northbridge, in this case called an I/O Hub (IOH). Socket LGA 1366 uses a land grid array format, so the pins are on the socket, rather than the processor. Socket LGA 1366 is shown in the figure below.

Socket LGA1366 (Socket B)Socket LGA1366 (Socket B)

Socket LGA 1366 is designed to interface between a processor and an IOH, which is the new name used for the northbridge component in supporting 5x-series chipsets. The LGA 1366 interface includes the following:

  • QPI (Quick Path Interconnect)—For data transfer between the processor and the IOH. QPI transfers two bytes per cycle at either 4.8 or 6.4 GT/s, resulting in a bandwidth of 9.6 or 12.8 GB/s.
  • DDR3 triple-channel—For direct connection between the memory controller integrated into the processor and DDR3 SDRAM modules in a triple-channel configuration.

LGA 1366 is designed for high-end PC, workstation, or server use. It supports configurations with multiple processors.

Socket LGA 1155

Socket LGA 1155 (also known as Socket H2) was introduced in January 2011 to support Intel’s Sandy Bridge (second-generation) Core ix-series processors, which now include Turbo Boost overclocking. Socket LGA 1155 uses a land grid array format, so the pins are on the socket, rather than the processor. Socket LGA 1155 uses the same cover plate as Socket 1156, but is not interchangeable with it. Socket LGA 1155 is also used by Intel’s Ivy Bridge (third-generation) Core ix-series processors. LGA 1155 supports up to 16 PCIe 3.0 lanes and eight PCIe 2.0 lanes.

Socket LGA 1155 is shown in the figure below.

Socket LGA1155 (Socket H2) before installing a processor.Socket LGA1155 (Socket H2) before installing a processor.

Socket LGA 2011

Socket LGA 2011 was introduced in November 2011 to support high-performance versions of Intel’s Sandy Bridge (second-generation) Core ix-series processors (Sandy Bridge-E), which now include Turbo Boost overclocking. LGA 2011 supports 40 PCIe 3.0 lanes, quad-channel memory addressing, and fully-unlocked processor multipliers.

Socket LGA 2011 uses a land grid array format, so the pins are on the socket, rather than the processor. Socket LGA 2011 is shown in the figure below.

Socket LGA2011 before installing a processor.Socket LGA2011 before installing a processor.

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