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CPU socket

In the case of CPU sockets, the development goes back to the basic constellations of Single-Inline-Package and Dual-Inline-Package, which were constantly expanded in their connection rows. Further development led to the square designs with connection contacts on all sides, as with the QFP package. As even these designs could not cope with the enormous connection requirements, sockets were developed for central processing units (CPU), caches, etc., whose connections are in the form of a square. Sockets were developed whose connections are located in the form of an array under the chip, as with Ball Grid Array (BGA) and Pin Grid Array (PGA) with their many variants.

Special versions of CPU sockets have more than 500 connection pins, whereby the pin assignment is one of the decisive criteria, others are the clock frequency and the operating voltage used

PGA so

PGA so

ckets In order to be able to classify the multitude of different sockets developed for the respective central processing units (CPU), a designation with numbers and letters was introduced for the CPU sockets. In the case of the three-digit designations, the number indicates the number of connection pins. Some processors are not plugged into sockets but into slots, while others are soldered onto the circuit board without sockets.

CPU sockets and slots for classic and modern CPUs

The following is a listing of sockets and slots:

Socket 1: ZIF socket for the 80486 with 168 pins or with 169 pins for the 80468 DX and 80468 SX. The supply voltage is 5 V, the max. clock frequency is 66 MHz

Socket 2: ZIF socket for 80486 DX2, 80468 SX2 and Xeon. Socket 2 has 238 pins and is designed for a supply voltage of 5V and a maximum clock frequency of 66 MHz.

Socket 3: ZIF socket with 237 pins for 80486 DX4 with a supply voltage of 3.3 V or 3.45 V and a max. clock frequency of 133 MHz. Since the 5x86 from Advanced Micro Devices (AMD) and Cyrix/IBM have fewer pins, they fit into all 486 sockets.

Socket 4: CPU socket for Pentium processors with 60 MHz and 66 MHz internal clock frequency and a supply voltage of 5V. Socket 4 has 273 pins and is designed for a max. clock frequency of 133 MHz. It was developed for the Pentium 60 and 66.

Overview of the different CPU sockets

Overview of the different CPU sockets

Socket 5: ZIF socket with 320 pins for Pentium processors of 60 MHz, 66 MHz, 75 MHz, 90 MHz and 133 MHz clock frequency and a supply voltage of 3.3V to 3.5V. It was used with Pentium CPUs with 75 MHz, 90 MHz and 100 MHz.

Socket 6: Socket 6 with 235 pins was never used.

Socket7: ZIF socket 7 was specified by AMD and Cyrix and is suitable for Pentium MMX with 133 MHz to 266 MHz, as well as for other Pentium processors with clock frequencies between 75 MHz and 200 MHz. Socket 7 is the most common socket for K5 and K6 processors from AMD, Cyrix M2, IBM 6x86MX, IDT Winchip and others. The socket has 321 pins, can be used up to clock frequencies of 500 MHz and is standard since 1999, next to slot 1.

Socket 7 S: This socket is similar to Socket 7, but has much improved specifications. So the AMD processor K6-2+ with 128 KBlevel 2 cache can be used with 500 MHz clock rate, as well as the K6-2 with up to 500 MHz and the K6-III with 400 MHz to 450 MHz. Furthermore the CPUs Cyrix MII, PR with 333 MHz and 366 MHz as well as the W2A from IDT with 266 MHz and 300 MHz. The Super Socket 7 has 21 contacts, but is specified for 100 MHz system clock and AGP graphics cards.

Socket 8: Only the Pentium Pro from Intel fits in this socket. Socket 8 has 387 pins and is designed for clock frequencies up to 333 MHz.



Socket 370 Socket 370: Socket with 370 pins for Celeron, Pentium III and Cyrix III. Socket 370 is available in PGA, PPGA and FC-PGA with clock rates up to 800 MHz. The CPUs have a level 2 cache

Socket 417: The Socket 417 has 417 pins and is suitable for the 64-bit CPU Itanium from Intel and HP. With Socket 417, the signal and power pins are shielded from each other, allowing signals to be transmitted at clock rates in excess of 2 GHz

Socket423: With 423 pins for Pentium 4, the socket is designed as a Zero Insertion Force (ZIF) socket and can be used for clock frequencies of up to 2 GHz.

Socket 441: Processor socket for the Atom processor. This is used in subnotebooks, UMPCs, netbooks and nettops.

Socket 478: This socket with 478 pins is for the Pentium 4 and the Celeron IV. It is designed for maximum clock frequencies of 3.066 GHz.

Socket 603: Socket 603 is the base socket for multiprocessor PCs with up to eight CPUs and clock speeds of at least 1 GHz. The Front Side Bus (FSB) has a clock frequency of 400 MHz. It is a ZIF socket with 603 connection contacts.

Connection diagram of the CPU socket 754

Connection diagram of the CPU socket 754

Socket 604: Socket 603 is the basic socket for multiprocessor PCs with up to eight CPUs and clock rates of at least 1 GHz. The frontside bus (FSB) has a clock frequency of 533 MHz.

Socket 754: For AMD Athlon 64 (Clawhammer) with a clock frequency of 2 GHz. With this socket a single channel controller came into the CPU.

Socket 940: A socket with 940 connectors for the Opteron from AMD. The maximum clock frequency is 1.8 GHz.

Socket 775 with opened pressure frame

Socket 775 with opened pressure frame

Socket 775: This socket was developed for Pentium 4 with clock frequencies between 2.8 GHz and 3.6 GHz and is also used by the Core 2 processor. It is an LGA socket with 775 pins, which is characterized by more ground lines and a better power supply. In addition, the socket 775 has advantages when inserting the central processing unit. For this purpose, the Socket 775 is opened, the central processing unit is inserted and the frame around the CPU is closed. This creates the necessary contact pressure for the contacts.


775 with pressure frame

775 with pressure frame

Socket 939: This socket was developed for the double core processor double Athlon (Athlon 64x2) and brought the second channel.

Socket 1366: The Socket 1366 was developed for the Core i7 from Intel. In this processor, the signal lines have increased significantly because each of the 20 Quick Path Interconnect (QPI) consists of two 20-bit wide channels. In total, the i7 socket has 1366 pins. When attached, the processor is pushed into the socket and locked in place with a lever.

Socket A: The ZIF Socket A is similar to the Socket 370 but not compatible with it. Socket A is a PGA socket with 462 pins and is only suitable for AMD processors Duron, Athlon, Spitfire with 800 MHz CPU clock, Thunderbird with 1 GHz CPU clock frequency and Mustang.

Socket M: Like Socket A, Socket M is a ZIF socket, but with 478 contacts. However, unlike the Socket 478, it has a different pinout. The Socket M is used for Intel's ULV processors Celeron M, Core-2 Solo and Duo, but is increasingly replaced by the CPU socket P.

Socket P: The CPU socket P replaces the socket M. It was developed for ULV processors. It is used in connection with the Intel CPUs Core-2-Duo, Core-2-Extreme and Pentium Dual-Core (mobile).

The CPUs are mounted vertically in the slots.

Slot 1

Slot 1

Slot 1: Slot 1 has 242 pins and is similar to an expansion slot. It was introduced with the development of the Pentium II and can also accommodate the Pentium III, as well as the Celeron processors. The CPU is located on the ladder board in a module along with the level 1 cache and the level 2 cache. Slot 1 is designed for maximum clock frequencies of 1 GHz.

Slot2: Slot 2 is the high-end processor socket for Intel's multiprocessors Pentium II Xeon and Pentium III Xeon

Slot A: Slot A has 242 pins like slot 1, but is mirror-inverted in design. This slot is suitable for the Athlon from Advanced Micro Devices (AMD) and is designed for maximum clock frequencies of 1 GHz.

Slot M: In order to achieve the highest possible bandwidth, the ground lines of this slot are routed directly to the CPU housing via an extra connector. Slot M is used for Intel processors IA-64, Merced.

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Englisch: CPU socket
Updated at: 11.04.2012
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