What Is LGA 1155? Explaining the Socket and Its Supported Processors

LGA 1155 is Intel’s desktop CPU socket for second- and third-generation Core chips, spanning Sandy Bridge and Ivy Bridge.

Two Intel generations, Sandy Bridge and Ivy Bridge, share a single socket — and that overlap is where most of the confusion starts. LGA 1155, which Intel also calls Socket H2, holds 1,155 contacts on a 40 x 40 grid and takes desktop chips from the Core i7-2xxx family down to the Celeron G16xx series.

Whether a specific chip boots in a specific board is a separate question, because the chipset and its BIOS decide the outcome more often than the socket label does. The table below maps the supported families, and the three checks that follow show how to confirm a swap before you pay for a processor.

What Processors Does LGA 1155 Support?

Intel lists five desktop processor families for this socket: Core i7, Core i5, Core i3, Pentium, and Celeron, split across the second-generation Sandy Bridge and third-generation Ivy Bridge model numbers.

Every chip on that list is a desktop part. Mobile processors with the same family names sit on a different socket, so a laptop chip with a matching number is not a candidate for one of these boards.

Intel’s socket design guide describes the physical layout as 1,155 contacts in a 40 x 40 grid with a 0.9144 mm pitch, the 36 mil figure board makers design to. The socket is a land grid array, so the contacts sit in the socket itself rather than on the processor — bent pins on the board, not on the chip, are the failure to watch for.

For a drop-in upgrade rather than a full rebuild, our tested CPU picks for LGA 1155 boards cover which used models still justify their price.

LGA 1155 Chipsets And BIOS: Where Compatibility Breaks Down

A matching socket does not guarantee a working build, because the chipset and its BIOS version decide which processors a board will recognize.

B65, H61, Q67, H67, P67, and Z68 are the Sandy Bridge-era chipsets built for this socket. Boards with those chipsets run second-generation processors as shipped, but many need a BIOS update before they will start with an Ivy Bridge chip, and some budget boards never received one.

Intel’s installation guide for LGA1155 desktop processors covers mounting and thermal setup for the socket; the compatibility answer comes from the board vendor’s CPU support list instead, which normally sits on the motherboard model’s support page.

Some used listings pair an Ivy Bridge chip with an H61 board and call it a working combo. That only holds if the seller already updated the BIOS, so ask for the revision string before paying.

Three checks settle the question before money changes hands:

1. Find the exact processor model number, then look it up on the motherboard vendor’s CPU support list for your board model.
2. Match the chip against Intel’s supported series for this socket: Core i7, i5, and i3 in 2xxx and 3xxx form, Pentium G6xx, G8xx, or G2xxx, and Celeron G4xx, G5xx, or G16xx.
3. Confirm the board is listed as LGA1155 or FCLGA1155, and stop if the processor does not settle onto the alignment notches on its own.

A model that appears on the vendor list beside a BIOS revision you already run is a swap worth attempting.

Where LGA 1155 Still Makes Sense Today

LGA 1155 stays useful for cheap office and home builds, but it is a legacy platform tied to 2011–2012-era Intel desktop processors and it is not a sensible base for a modern mainstream machine.

Complete towers sell for very little secondhand, and a working quad-core board with a Core i5 still handles browsing, documents, and media playback without strain. A dying power supply or a failed drive is the usual reason these machines get retired, so budget for those parts before the processor.

Xeon E3 chips turn up in LGA 1155 listings too, but Intel’s public support article covers desktop processors only. Xeon support depends on the individual board and chipset, so treat any listing that promises it as board-specific until the vendor list confirms it.

Operating system support is the other limit worth checking, since current Windows releases officially target much newer Intel processors than these. Buying a complete refurbished tower usually costs less than assembling parts, so confirm the board model, confirm the chip on the vendor list, then compare the total against a newer used office PC.