A CPU (the green square with rubber pads in each corner) sits in a socket on the motherboard.
CPU sockets are standard in today's desktop and notebook computers. Previously, it was more common to have the CPU soldered into the motherboard, making replacements and upgrades impossible. Socket designs change over time, although AMD uses the same sockets far longer than Intel does. This makes upgrading and maintaining an AMD-based system much cheaper in many cases. By contrast, Intel uses a new socket type with every new range of processors that is not backward-compatible. This means that when upgrading an Intel-based desktop, you will often have to change the motherboard and, sometimes, even the memory.
Intel LGA1155
The LGA1155 socket is a replacement for the older LGA1156. The LGA1155 is used for most of Intel's Core i3, i5 and i7 processors as well as its server processors, the Xeon product line. The socket is not backward-compatible with LGA1156, although heat sinks and fans designed for either one will be compatible with both. LGA stands for "Land Grid Array."
Intel LGA1366
The Intel LGA1366 is used for the highest-end Intel processors from the Core i7 range. The socket provides 1366 pins, hence the name. This socket is also known as Socket B. The LGA1366 is used in some server computers with Xeon processors.
AMD AM2
The AMD AM2 socket supports dual-channel DDR-II memory and processors from the Athlon and Phenom ranges. The socket has been one of the longest-lasting designs. Processors designed for the AM2 socket will also work in the AM3 or AM2+ sockets that succeeded the original AM2 design. The AM2 sockets have 940 pins.
AMD AM2+
Also with 940 pins is the AM2+ socket, the immediate successor to the AM2 sockets. This is a midway migration socket designed for backward-compatibility. Since both DDR-II and a DDR-III memory controllers are available, the AM2+ socket will work with both AM2 and AM3 CPUs. An AM2+ processor will not, however, work on an AM3 motherboard because the processor does not have a DDR-III memory controller.
AMD AM3
With 941 pins, the AM3 socket is the main replacement for AM2 sockets. It provides a DDRIII memory controller for enhanced performance and compatibility with the latest and most powerful quad- and hex-core processors from the Athlon II and Phenom II processors.
Tags: processors from, Athlon Phenom, DDR-III memory, from Athlon, from Athlon Phenom