Socket 940
Following the ageless Socket A, Socket 940 is considered one of the most short-lived type of CPU. The socket is covered entirely with pin holes, 940 to be exact. Launched concurrently with the Socket 754, Socket 940 was primarily targeted towards high-end and server/workstation use. For the user, one of the biggest disadvantages associated with this package is the required use of expensive ECC and registered system memory. AMD used this socket for the Athlon 64 FX-51 and FX-53 as well as several Opteron processors. All Socket 940 processors are 64-bit CPUs, use .13 micron process, and they have a 1MB L2 cache. Note that AMD is planning to release a new package dubbed “Socket AM2″ - they also have 940 pins on the processor, but they are by no means compatible with the older Socket 940.

AMD’s Socket 940, 939, and 754, all based on the K8 technology, have bus speeds upwards 1Ghz.

Socket 754
Socket 754 is the budget-friendly Socket 940 compliment. Using a 754-pin configuration, AMD implemented its new K8 architecture in offering 64-bit processing to the mainstream consumers. Socket 754 is used in earlier versions of the low-end the Athlon 64 line (Newcastle/Clawhammer cores) as well as the middle to higher-end Sempron/64-bit Sempron line. While S754 is still used commonly for Semprons, it is being phased out of the Athlon 64 line in favor of the Socket 939. All Socket 754 packages use either a 512k or a 1MB L2 cache. Socket 754 does not offer dual channeling capability.

Socket 775 (aka Socket T, LGA775)
Socket 775 is an LGA processors - Land Grid Array. All 775 pins between the motherboard and processor are now located on the socket instead of soldered onto the processor. There is speculation that Intel shifted to an LGA system so that the motherboard manufacturers will be responsible for the pins. The 297 pin increased from the Socket 478 was meant to alleviate heat dissipation as well as to better distribute the workload throughout the pins. All of Intel’s current mainstream processors use LGA775, including latter-Pentium 4’s, Pentium D’s, and Pentium Extreme Editions. S775 ranges from 2.4 Ghz all the way up to 3.8 Ghz. All processors either have a 1MB L2 cache or a 2MB L2 cache and either a .09 micron or .065 micron process. Retail socket 775 processors come equipped with a fairly large retail heat sink that attaches using push pins as opposed to the conventional lever arms found in earlier Pentium 4’s.

Socket 939
Socket 939 accepts non-ECC non-registered memory with the option of a dual channel configuration. AMD widely uses socket 939 today, including the Athlon 64, Athlon 64 FX (FX-55 and up), Athlon 64 X2, Turion 64, and select Opteron’s line of processors. They range from a 512k L2 cache, to a 1MB L2 cache, to a 2MB (two 1MB independent dual core) L2 cache. Like all of its previous processors and unlike Intel’s Socket T, Socket 939 is a PGA processor with the pins on the actual processor. All Socket 939 processors are either based on a .09 micron or a .13 micron process.

Slockets
The slocket is a weird little contraption. It’s basically Slot 1 to Socket 370 adapter. It comes in other flavors too. By doing a bunch of electrical work-arounds, it is able to successfully reroute the currents and make the different interfaces adapt. Some of them even have cute little electrical tricks that allow things such as dual-processor or overclocking despite the clock-locking.