What Is Socket AM3?

Socket AM3 is a hardware standard for the installation of central processing units (CPUs) on desktop computers. More specifically, it is a type of CPU interface that accommodates certain models of AMD processors. The 941-hole AM3 CPU socket was introduced by AMD in February 2009 to take advantage of then-recent memory types and allow for higher-performing CPUs.

As of 2011, socket AM3 is the most current CPU socket for AMD desktop processors, serving as a replacement for the previous generation sockets AM2 and AM2+. The newer processor interface is intended to support double data rate type three synchronous dynamic random access memory (DDR3 SDRAM), a memory standard that has at least twice the bandwidth of previous types to move and store data, resulting in the potential for a faster system. The AM3 socket also allows AMD to further increase the CPU bus speed — the rate at which the processor can internally manage data — compared to older sockets.

Although socket AM3 represents a newer design than socket AM2 and AM2+, the pin configuration between the CPUs for the different sockets is nearly identical — 938 pins versus 940 on the older chips. A CPU designed for socket AM2 or AM2+ cannot be used on a socket AM3 motherboard, but it is possible to utilize an AM3-based CPU on a socket AM2 or AM2+ motherboard. This use comes with two caveats: First, it assumes the computer’s motherboard will be flashed with the latest updates to ensure the newer AM3 CPU is supported. Second, performance with the AM3 processor will be reduced on the older chipset. The AM2- or AM2+-based motherboard will cause the AM3 CPU bus speed to be restricted to the highest speed the older board will support.

The similar layout of the newer socket to socket AM2 and socket AM2+ brings two other advantages. First, like the previous designs, socket AM3 utilizes a zero insertion force (ZIF) protocol, meaning the chip will simply drop into place once correctly positioned on the motherboard, reducing the chance the CPU could be damaged during installation. Second, the design of the sockets is so similar that CPU coolers designed for the older chipsets can be used on AM3 motherboards and vice versa.

The socket AM3 platform supports two lines of AMD processors. The AMD Athlon™ II has speeds ranging between 1.6 gigahertz (GHz) and 3.4 GHz, with from two to four cores per processor. The higher-performing AMD Phenom™ II CPUs also are AM3-based and contain from two to six cores with speeds ranging from 2.5 GHz to 3.7 GHz. All of these processors are for desktop only and are manufactured on a 45-nanometer process.

As of June 2011, AMD had plans to roll out a slightly modified socket AM3+. This new processor layout is intended to support the transition to a higher-performing platform code-named “Bulldozer”. It was expected that socket AM3+ would support existing AM3 CPUs.