Re: Why do sockets matter?
He means you can't.
Anyway, to expand on it, basically different generations of CPU's use different sockets.
This is mainly because as CPU technology progresses, the voltages required to operated the smaller transistors is less, however there are far more transistors in each new generation of CPU's so you require more current. If all the current required for a new CPU was to pass through the same ammount of pins, say as an original P3 (370) it would melt the pins. Intel went with the LGA platform to get around this too, so a greater area of the 'stubs' are in contace with the 'socket'.
For each new generation of CPUs there are added features as well that would require more pins. Take the AMD Athlon 64 Skt 939 CPU's for example, these have dual channel memory controllers (128bits wide) wheras the SKT 754 only have a single channel memory controller (64bits wide). You could bet that some of the extra pins are needed for the extra memory channel.
Not all different sockets are for such reasons though. Some mearly to prepare the motherboards for future CPUs, and is the case with Intels switch from the Slot 1 to the Skt 370, Skt462 to Skt478, and AMDs Slot A to Skt A. If you were to compare equivelently clocked CPU's from each of these pair, they'ed perform identical.
And remember, a lot of the extra pins are also reserved, not being used at all. Just for future proofing sake.
Delta: "What's wrong Chris?? Chris: "I miss my old Cyrix"