View source for LGA 775

{{short description|Intel desktop CPU socket}}
{{CPU socket
| name         = LGA 775
| image        = [[File:LGA 775 Socket T.jpg|300px]]
| formfactors  = [[flip chip|Flip-chip]] land grid array (FCLGA)
| type         = [[Land grid array]]-[[Zero insertion force]] (LGA-ZIF)
| contacts     = 775
| protocol     = AGTL+
| fsb          = {{ubl|133 MHz (533 MT/s)|200 MHz (800 MT/s)|266 MHz (1066 MT/s)|333 MHz (1333 MT/s)|400 MHz (1600 MT/s)}}
| dimensions   = 37.5 × 37.5 mm<ref>{{cite web |title=Intel Pentium 4 Datasheet |url=http://download.intel.com/design/Pentium4/datashts/303128.pdf |website=Intel |language=en-US |archive-url=https://web.archive.org/web/20080224003953/http://download.intel.com/design/Pentium4/datashts/303128.pdf |archive-date=February 24, 2008}}</ref>  <br/>1,406.25 mm²
| processors   = {{ubl|[[Intel]] [[Pentium 4]] (2.66–3.80 GHz)|[[Intel]] [[Celeron#Celeron D|Celeron D]] (2.53–3.60 GHz)|[[Intel]] [[Pentium 4#Gallatin .28Extreme Edition.29|Pentium 4 Extreme Edition]]<br/>&nbsp;(3.40–3.73 GHz)|[[Intel]] [[Pentium D]] (2.66–3.60 GHz)|[[Pentium D|Pentium Extreme Edition]]<br/>&nbsp;(3.20–3.73 GHz)|[[Pentium Dual-Core]] (1.40–3.33 GHz)|[[Intel Core 2|Intel Core 2 Duo]] (1.60–3.33 GHz)|[[Intel Core 2|Intel Core 2 Quad]] (2.33–3.00 GHz)|[[Intel Core 2|Intel Core 2 Extreme]] (2.66–3.20 GHz)|[[Intel]] [[Xeon]] (1.86–3.40 GHz)|[[Intel]] [[Celeron]] (1.60–2.40 GHz)}}
| predecessor = [[Socket 478]]
| successor   = {{ubl|[[LGA 1156]] (desktops and low-end servers)|[[LGA 1366]] (high-end desktops and some low-end to mid-end servers)}}
| memory      = <br> [[DDR SDRAM|DDR]] (also known as DDR1) <br> [[DDR2 SDRAM|DDR2]] <br> [[DDR3 SDRAM|DDR3]]
|designed-by=Intel|release-date=2004 (21 years ago)|voltage=1.2 V - 1.5 V|variant=[[LGA 771]] (Socket J)|manufacturer=Intel}}

'''LGA 775''' ([[land grid array]] 775), also known as '''Socket T''', is an [[Intel]] desktop [[CPU socket]]. Unlike [[Pin grid array|PGA]] CPU sockets, such as its predecessor [[Socket 478]], LGA 775 has no socket holes; instead, it has 775 protruding pins which touch contact points on the underside of the [[Central processing unit|processor]] (CPU).<ref name="asisupport">{{cite web|url=http://www.asisupport.com/ts_training_LGA775.htm|archive-url=https://web.archive.org/web/20071213023229/http://www.asisupport.com/ts_training_LGA775.htm|archive-date=December 13, 2007|title=New P4 Socket Type LGA 775 (Socket T)|access-date=2007-03-14|website=asisupport.com}}</ref>

Intel started selling LGA 775 (Socket T) CPUs with the 64-bit version of their 90 nm "Prescott"-based [[Pentium 4|Pentium 4 HT]].<ref name="asisupport" />

The socket had an unusually long life span, lasting 7 years until the last processors supporting it ceased production in 2011. The socket was superseded by the [[LGA 1156]] (Socket H) and [[LGA 1366]] (Socket B) sockets.

== LGA 775 processors ==
[[File:Lga775cpus.jpg|thumb|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]]
* [[Core 2 Extreme]]

== Heatsink design ==
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]].

==Chipsets==

'''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 Chipsets ====
{{further|List of Intel chipsets#Core 2 chipsets}}
*Lakeport: 945PL / 945P / 945G / 945GC / 945GZ / 955X / 946PL / 946GZ P
*Broadwater: i955X / i946 / 946GZ / PL / 965 / i975 / Q965 / P965 / G965 / Q963 / i975X
*Bearlake: X35 / P35 / Q35 / G35 / P33 / G33 / Q33 / P31 / G31 / X38 / X48
*Eaglelake: P45 / P43 / G45 / G43 / G41 / B43 / Q43 / Q45<br />945PLS3

=== SiS ===
{{further|Silicon Integrated Systems}}
* SiS 649
* 649FX
* 655
* 656
* 656FX
* 662
* 671
* 671FX
* 671DX
* 672

=== VIA ===
{{further|VIA Technologies}}
* PT800
* PM800
* PT880
* PM880
* P4M800
* P4M800 Pro
* PT880 Pro
** Supports both [[Accelerated Graphics Port|AGP]] and PCI-Express at the same time, however only one port can be used at a time. A similar design can also be found in some [[Socket 939]] boards.
* PT880 Ultra
* PT894
* PT894 Pro
* P4M890
* PT890
* P4M900

=== ATI ===
{{further|ATI Technologies}}
* ATI Radeon Xpress 200
* ATI Radeon Xpress 1250
* ATI CrossFire Xpress 3200

=== Nvidia ===
{{further|Nvidia}}
* nForce4 Ultra
* nForce4 SLI XE
* nForce4 SLI;
* nForce4 SLI X16
* [[Comparison of Nvidia nForce chipsets#For Intel processors 2|nForce 570 SLI]]
* nForce 590 SLI
* nForce 610i
* nForce 620i
* nForce 630i
* nForce 650i Ultra
* nForce 650i SLI
* nForce 680i LT SLI
* nForce 680i SLI
* nForce 730i
* nForce 740i SLI
* nForce 750i SLI
* nForce 760i SLI
* nForce 780i SLI
* nForce 790i SLI
* GeForce 9300
* GeForce 9400<ref name=":0">{{cite web|title=ASRock > Motherboard Series|url=http://www.asrock.com/mb/index.asp?s=775|website=[[ASRock]]|access-date=15 March 2015|archive-url=https://web.archive.org/web/20150315101243/http://www.asrock.com/mb/index.asp?s=775|archive-date=15 March 2015}}</ref>

==Improvements in heat dissipation==
{{Unreferenced section|date=March 2018}}
[[File:Core 2 Duo E7500 2.93GHz.jpg|thumbnail|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.<ref>{{Cite web |date=2025-02-06 |title=Intel Core 2 Duo E7500 Specs |url=https://www.techpowerup.com/cpu-specs/core-2-duo-e7500.c1530 |access-date=2025-02-06 |website=TechPowerUp |language=en}}</ref> 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 [[Socket 370]] and the "clamshell" four-point connection of [[Socket 478]]. This was done to avoid the reputed danger of the heat sinks/fans of pre-built computers falling off in transit.<ref>{{Cite web |title=LGA775 Socket |url=https://www.intel.com/Assets/PDF/designguide/302666.pdf |website=www.intel.com}}</ref> 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 [[Intel Core 2|Core 2]] processors run at much lower temperatures than the Prescott CPUs they replaced.<ref>{{Cite web |date=2010-10-04 |title=Intel core 2 duo operating temperature? |url=https://community.intel.com/t5/Processors/Intel-core-2-duo-operating-temperature/m-p/316827 |access-date=2025-02-06 |website=community.intel.com |language=en}}</ref>

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.<ref>{{Cite web |title=What is thermal design power (TDP)? |url=https://www.lenovo.com/us/en/glossary/what-is-thermal-design-power/?orgRef=https%253A%252F%252Fwww.google.com%252F&srsltid=AfmBOoonghjlGHagvNd6m1hJP_WQzeh7mo3c2PjcpwY4PTvvGcPqjJCh |website=www.lenovo.com}}</ref>

==LGA 775 mechanical load limits==
[[File:Intel CPU Pentium 4 640 Prescott bottom.jpg|thumb|right|250px|The LGA 775 contact points on the underside of a [[Pentium 4]] Prescott [[central processing unit|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.
{| class="wikitable" style="font-size: 95%; text-align: center;"
|-
! rowspan=1 style="width:12em" | Location
! rowspan=1 | Dynamic
! rowspan=1 | Static
|-
| IHS Surface
| 756 [[Newton (unit)|N]] (170 [[Pound-force|lb<sub>f</sub>]]) (77 [[kilogram-force|kp]])
| 311 N (70&nbsp;lb<sub>f</sub>) (31 kp)
|}
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.

==LGA 775 compatibility==
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.

== Virtualization capabilities ==
Some [[Core 2]] and other LGA 775 processors are capable of [[Intel VT-x|hardware-accelerated virtualization]]. However, more recent hypervisors might not be compatible with these CPUs because they lack support for [[Second_Level_Address_Translation#EPT|Extended Page Tables]].

==See also==
* [[List of Intel processors]]
* [[List of Intel Pentium 4 processors]]
* [[List of Intel Core 2 processors]]
* [[List of Intel Xeon processors]]

==References==
{{Reflist}}
==External links==
*{{commons category-inline|Socket 775}}

{{intelsock}}

{{DEFAULTSORT:Lga 775}}
[[Category:Intel CPU sockets|LGA 0775]]