LGA 775

A selection of LGA 775 CPUs

(Note: Some of the processors listed here might not work on newer Intel based chipsets; see "LGA 775 compatibility" below.)

• Pentium 4
• Pentium 4 Extreme Edition
• Pentium D
• Celeron/Celeron D
• Pentium Dual-Core
• Pentium Extreme Edition
• Core 2 Duo/Core 2 Quad

For LGA 775, the distance between the screw-holes for the heatsink is 72 mm. Such heat-sinks are not interchangeable with heatsinks for sockets that have a distance of 75 mm, such as LGA 1156, LGA 1155, LGA 1150, LGA 1151 and LGA 1200.

LGA 775 was the last Intel socket for desktops for which third-party companies manufactured chipsets. Nvidia was the last third-party manufacturer of LGA 775 chipsets (its final product was MCP7A family, marketed as GeForce 9300/9400, launched in October 2008), as other third-parties discontinued their products earlier. All chipsets for superseding sockets were exclusively designed and manufactured by Intel, a practice later also adopted by AMD when they first launched APUs in 2011 (Socket AM3+ processors, also launched in 2011, were usually paired with motherboard with AMD chipsets, but some motherboards using third-party chipsets were also manufactured, usually with Nvidia chipsets, as the Socket AM3+ design was directly extended from the earlier Socket AM3 design).

Intel Core 2 Duo E7500 2.93 GHz installed into LGA 775 socket

The force from the load plate ensures that the processor is completely level, giving the CPU's upper surface optimal contact with the heat sink or cold-water block fixed onto the top of the CPU to carry away the heat generated by the CPU. This socket also introduces a new method of connecting the heat dissipation interface to the chip surface and motherboard. With LGA 775, the heat dissipation interface is connected directly to the motherboard on four points, compared with the two connections of the Socket 370 and the "clamshell" four-point connection of the Socket 478. This was done to avoid the reputed danger of the heat sinks/fans of pre-built computers falling off in transit. LGA 775 was announced to have better heat dissipation properties than the Socket 478 it was designed to replace, but the Prescott core CPUs (in their early incarnations) ran much hotter than the previous Northwood-core Pentium 4 CPUs, and this initially neutralized the benefits of better heat transfer. However, the later Core 2 processors run at much lower temperatures than the Prescott CPUs they replaced.

Processors with lower TDP and clock speeds only used Thermal Interface Compound in between the die and the integrated heat spreader (IHS), while processors with higher TDP and clock speeds have the die soldered directly to the IHS, allowing for better heat transfer between the CPU and the integrated heat spreader.

The LGA 775 contact points on the underside of a Pentium 4 Prescott CPU

All LGA 775 processors have the following mechanical maximum load limits which should not be exceeded during heat sink assembly, shipping conditions, or standard use. Load above those limits could crack the processor die and make it unusable. The limits are included in the table below.

The transition to the LGA packaging has lowered those load limits, which are smaller than the load limits of Socket 478 processors but they are bigger than Socket 370, Socket 423 and Socket A processors, which were fragile. They are large enough to ensure that processors will not crack.

Compatibility is quite variable, as earlier chipsets (Intel 915 and below) tend to support only single core NetBurst Pentium 4 and Celeron CPUs at an FSB of 533/800 MT/s.

Intermediate chipsets (e.g. Intel 945) commonly support both single core Pentium 4-based CPUs as well as dual core Pentium D processors. Some motherboards using the 945 chipset could be given a BIOS upgrade to support 65nm Core-based processors. Other chipsets have varying levels of CPU support, generally following the release of contemporary CPUs, as LGA 775 CPU support is a complicated mixture of chipset capability, voltage regulator limitations and BIOS support. For example, the newer Q45 chipset does not support NetBurst-based CPUs such as the Pentium 4, Pentium D, Pentium Extreme Edition, and Celeron D.

Some Core 2 and other Socket 775 processors are capable of hardware-accelerated virtualization. However, more recent hypervisors might not be compatible with these CPUs because they lack support for Extended Page Tables.

• List of Intel processors
• List of Intel Pentium 4 processors
• List of Intel Core 2 processors
• List of Intel Xeon processors

• Media related to Socket 775 at Wikimedia Commons