LGA 1155

LGA 1155
Name	LGA 1155
Other names	Socket H2
Type	Land grid array
Contacts	1155
Protocol	DMI, PCI Express, DisplayPort, HDMI
Processor	Sandy Bridge, Ivy Bridge
Predecessor	LGA 1156
Successor	LGA 1150

LGA 1155, also known by its codename Socket H2, is a land grid array CPU socket designed by Intel Corporation for its desktop and server central processing units. Introduced in January 2011 alongside the Sandy Bridge microarchitecture, it served as the primary platform for two successive generations of Intel processors. The socket represented a significant evolution from its predecessor, LGA 1156, by integrating key platform components directly onto the processor die, thereby improving performance and efficiency. Its widespread adoption in consumer desktop computers and entry-level servers made it one of the most successful and enduring mainstream sockets of its era.

Overview

The launch of LGA 1155 coincided with Intel's "Tick-Tock model" strategy, where it represented the "tock" phase with the new Sandy Bridge design. This socket was a critical component in systems built around the Intel Xeon E3 series for servers and the Core i7, Core i5, and Core i3 families for desktops. A key innovation was the relocation of the memory controller and PCI Express lanes from the platform controller hub to the CPU itself, a design philosophy pioneered earlier with the AMD64 architecture. This integration reduced latency and increased data throughput for connected components like graphics processing units and RAM. The physical socket, manufactured by companies like Foxconn, maintained the same mounting mechanism as LGA 1156 but was electrically and pin-incompatible, preventing direct processor upgrades between the generations.

Technical specifications

LGA 1155 features 1155 protruding pins that make contact with pads on the underside of the processor. It supports a Direct Media Interface (DMI) 2.0 link for communication with the chipset, doubling the bandwidth compared to the DMI 1.0 used with LGA 1156. The integrated memory controller officially supports dual-channel DDR3 SDRAM at speeds up to DDR3-1333 for Sandy Bridge and DDR3-1600 for Ivy Bridge, though many motherboards allowed higher speeds via overclocking. Processors for this socket contain 16 PCI Express 2.0 lanes (Sandy Bridge) or 3.0 lanes (Ivy Bridge) directly from the CPU, primarily used for a primary graphics card. Thermal design power (TDP) ratings for supported CPUs ranged from 35 watts for low-power models to 95 watts for high-performance quad-core parts, requiring compatible heat sinks and cooling solutions.

Supported processors

LGA 1155 exclusively supports Intel's Sandy Bridge (2nd Generation Core) and Ivy Bridge (3rd Generation Core) microarchitectures. The desktop lineup included the Pentium, Celeron, Core i3, Core i5, and Core i7 series, with flagship models like the Core i7-2700K and Core i7-3770K being popular among enthusiasts. For the server and workstation market, the socket was used for the Intel Xeon E3-1200 and E3-1200 v2 families, which brought ECC memory support to the platform. While the socket is physically identical for both generations, a BIOS update is typically required for a motherboard launched with Sandy Bridge to support a subsequent Ivy Bridge CPU, due to differences in integrated voltage regulator requirements and microcode.

Compatible chipsets

The primary chipsets for LGA 1155 are the Intel 6 Series (codenamed Cougar Point) for Sandy Bridge and the Intel 7 Series (codenamed Panther Point) for Ivy Bridge. Key consumer chipsets included the high-end Z68 and Z77, which supported CPU and memory overclocking, as well as the business-oriented Q67 and Q77. Mainstream options like the H67, H77, P67, and B75 offered varying balances of features such as Intel Rapid Storage Technology, Intel Smart Response Technology, and support for USB 3.0. The C206 and C216 chipsets were designed for the Intel Xeon E3 platform, adding support for ECC memory and Intel vPro technology.

Motherboard and system implementation

Motherboards for LGA 1155 were produced by all major manufacturers, including ASUS, Gigabyte Technology, MSI, and ASRock. These boards came in standard ATX, microATX, and Mini-ITX form factors, enabling a wide range of system builds from compact home theater PCs to high-performance gaming rigs. Implementation varied significantly; premium models featured robust voltage regulator modules, multiple PCI Express slots for NVIDIA SLI or AMD CrossFire configurations, and SATA 6 Gbit/s ports. The socket's longevity meant motherboard designs evolved to include newer connectivity like USB 3.0 controllers from Renesas Electronics and improved audio codecs from Realtek.

Successors and market position

LGA 1155 was succeeded by LGA 1150 in 2013, which introduced support for the Haswell microarchitecture and a new power delivery design. Despite this, LGA 1155 maintained a strong market position due to its excellent performance-per-watt ratio, mature platform stability, and the significant IPC improvement Sandy Bridge offered over prior architectures like Nehalem. Its role was pivotal in consolidating Intel's dominance in the mainstream CPU market against contemporary offerings from Advanced Micro Devices such as the Bulldozer-based FX series. The platform remains a common fixture in the secondary market and in legacy corporate deployments, testament to its widespread adoption and reliability during its production lifespan.

Category:CPU sockets Category:Intel microprocessors Category:Computer hardware standards