Intel Core i5-2550K socket: LGA 1155

What the Core i5-2550K is

Intel Core i5-2550K is an unlocked quad core Sandy Bridge desktop processor that Intel released in January 2012 for overclocking towers with discrete graphics. It runs at 3.4 GHz base with Turbo Boost 2.0 to 3.8 GHz, with 6 MB Intel Smart Cache and 4 threads. Power is rated at 95 W on a 32 nm process. The K suffix unlocks the multiplier, while the missing graphics block separates it from the 2500K at nearby clocks.

No iGPU means every monitor needs a PCIe card, even for office work. In return overclockers avoid paying power for graphics that would sit idle. The chip keeps the dual channel DDR3 controller, AVX and virtualization support of the Sandy family.

Overclocking needs a P67, Z68, Z77 or Z75 board with multiplier control and cooling above stock. At stock the chip behaves like a fast 95 W quad with strong single thread bursts. Towers pair it with 8 GB of DDR3 and a discrete card. The How to find your CPU socket type guide helps confirm the board before a used K purchase.

Socket and motherboard compatibility

The Core i5-2550K fits LGA 1155 in FCLGA1155 form. It boots on 6 series and 7 series boards, but multiplier control needs P67, Z68, Z77 or Z75 with the right firmware. H77 and B75 run the chip at stock clocks without overclocking. A discrete card is mandatory on every board, since no display comes from the chip.

Power at 95 W suits standard tower delivery, though overclocking raises draw beyond the rating. A P67 or Z68 ATX board with a tower cooler is the expected pairing. The Socket vs chipset: what decides whether a CPU works guide explains the chipset split, and Intel Core i7-2600K shows the unlocked Sandy i7 with graphics on the same socket.

Memory, PCIe and cooling

Memory support is DDR3-1066 and 1333, two channels, up to 32 GB at stock. Faster memory through overclocking profiles is possible on P and Z boards. Two matched DIMMs feed four cores. ECC is not supported.

PCI Express is 16 lanes from the CPU at PCIe 2.0. K builds of the period paired the chip with a mid to high range 2011 card, which four Sandy cores at 3.4 GHz feed well.

Cooling at stock follows the 95 W pattern, but overclocking wants a tower or closed loop with headroom. The 75 × 75 mm mount accepts a wide range of LGA coolers. K chips ship without a cooler in many boxes, so plan for one.

Upgrade paths

On LGA 1155 the Core i5-2550K is already near the top of the Sandy i5 range. The remaining same socket steps are Ivy K parts with newer graphics and lower power, where the board BIOS is current. Memory, storage and the graphics card carry over in those swaps.

A platform move to DDR4 boards such as LGA 1200 needs a new board, new RAM and a new mount. Keep the 2550K tower for tuning work where the unlocked multiplier without an iGPU still appeals.