Slot 2
Slot 2 is essentially a 330-pin version of the Slot 12 interface, designed for the Xeon processors. The most effective difference between Slot 1 and Slot 2, though, is that the Slot 2 design allows the CPU to communicate with the L2 cache at the CPU’s full clock speed. In contrast, Slot 1 only supports communication between the L2 cache and CPU at half the CPU’s clock speed.

Slot A
This is the proprietary slot design AMD decided to use with the Athlon processor. Design wise, it is similar to the Slot 1. But, Slot A uses a different protocol, called EV6. Using this bus protocol, which was created by Digital, AMD can increase the RAM to CPU data transfer to 200MHz, giving us a 200MHz frontside bus. This is achieved by diong data transfer on both the rise and fall of the clock cycle, effectively doubling the normal 100MHz bus. Slot A stayed in the ballgame for awhile and we saw many motherboards come out using this slot, therefore allowing AMD’s Athlon to propogate into the market. When both Intel and AMD moved back into socketed processors, though, this slot was dumped along with Slot 1.

Socket 370
Socket 370 is named for the number of pins this particular socket has.  After Intel found a way to cheaply put the cache of a CPU on the die itself, the benefit of having a processor on a daughtercard was minimized. With that, it became not only an added cost to continue to produce Slot 1 processors, but also a useless cost. Intel then took the chip off of the PCB, and created Socket 370.  It’s basically Socket 7 with an extra row of pins on all four sides.  The first processors to use it were the PPGA Celerons, then quickly following were the FC-PGA Pentium III processors along with the Celeron II line. Socket 370 chips can be placed on a daughercard just like Socket 8 chips in order to fid into a Slot 1 Interface.  Socket 370 is also made to use previous Socket 7 heatsinks, although most of these cooling devices are too small and weak to cool these modern processors. This Socket is used for Pentium III, Celeron, and Celeron II processors.

Socket 462 (aka Socket A)
Just as Intel found it cheaper to leave the PCB off of it’s processors, AMD did the same thing and for the same reasons.  Socket A encompasses a large range of processors, starting off with the .18 micron Athlons and Durons, and ending with the .13 micron Athlon XP’s and earlier Semprons.  It supports the 200MHz, the 266MHz, as well as the 333Mhz EV6 bus.  Unlike Socket 370, Socket 7 heat sinks cannot be used on Socket A’s, but again, Socket 7 heat sinks just aren’t powerful enough anyway for these faster Socket A processors. Also, unlike Socket 370, there is no daughter card that provides Socket A chips to be plugged into Slot A interfaces.  Socket A also offers many more pins than Socket 370, 462 in total. Socket 370 chips cannot plug into Socket A, and vice-versa. Admits stiff competition, AMD stuck with Socket A for more than four long years - from June 2000 onto late February 2005.

Socket 423/478
Socket 423 is the older socket of the Pentium 4 sockets. Socket 423 Pentium 4’s are larger and use 423 pins. They are noticeable because they have a green plate around the processor core from which the actual pins protrude. The 423-pin Pentium 4’s are also noticeably larger than the 478-pin units. Intel quickly moved on to the socket 478 format, supporting the newer designed 478-pin P4’s. While the two sockets were essentially equals in terms of performance, socket 478 is now the Pentium 4 standard. Intel just is not making 423-pin processors anymore, and these chips are topped out at 2 GHz. Also, all the 512 KB L2 cache Pentium 4’s come on Socket 478. Mounting of the CPU coolers are also different for the two sockets.

Socket 603/604
These are Intel’s Xeon processor sockets, succeeding slot 2. Because Intel found an inexpensive way of putting cache on the processor itself, the Socket 603/604 incorporates upwards 4MB L2 cache on these CPUs with an added upwards 8MB L3 cache on select socket 604 models. Intel also cranked up the front side bus - ranging from a 400Mhz FSB up to a 800Mhz FSB. All Socket 604 CPUs have EM64T (64-bit).