LGA 1156, also known as Socket H or H1, is an Intel desktop CPU socket. LGA stands for land grid array. Its incompatible successor is LGA 1155. The last processors supporting it ceased production in 2011. LGA 1156, along with LGA 1366, were designed to replace LGA 775. Whereas LGA 775 processors connect to a northbridge using the Front Side Bus, LGA 1156 processors integrate the features traditionally located on a northbridge within the processor itself. The LGA 1156 socket allows the following connections to be made from the processor to the rest of the system:
PCI-Express 2.0 ×16 for communication with a graphics card. Some processors allow this connection to be divided into two ×8 lanes to connect two graphics cards. Some motherboard manufacturers use Nvidia's NF200 chip to allow even more graphics cards to be used.
DMI for communication with the Platform Controller Hub. This consists of a PCI-Express 2.0 ×4 connection.
FDI for communication with the PCH. This consists of two DisplayPort connections.
Two memory channels for communication with DDR3 SDRAM. The clock speed of the memory that is supported will depend on the processor.
The LGA 1156 and LGA 1366 sockets and processors were discontinued sometime in 2012, having been superseded by the LGA 1155 and LGA 2011 respectively.
Heatsink
For LGA 1156 the 4 holes for fastening the heatsink to the motherboard are placed in a square with a lateral length of 75 mm. This configuration was retained for the later, LGA 1155, LGA 1150, and LGA 1151 sockets meaning that cooling solutions should generally be interchangeable.
All LGA 1156 processors and motherboards made to date are interoperable, making it possible to switch between a Celeron, Pentium, Core i3 or Core i5 with integrated graphics and a Core i5 or Core i7 without graphics. However, using a chip with integrated graphics on a P55 motherboard will not allow use of the on-board graphics processor, and likewise, using a chip without integrated graphics on a H55, H57 or Q57 motherboard will not allow use of the motherboard's graphics ports.
Supported chipsets
The Desktop chipsets that support LGA 1156 are Intel's H55, H57, H61, P55, and Q57. Server chipsets supporting the socket are Intel's 3400, 3420 and 3450.
