A custom PC configuration guide. © 2000,2001,2002 by Jef Poskanzer.
Here's a table showing the most important aspects of the various CPUs.
|connector||L2 cache speed||FSB speed||memory speed|
|Pentium 4 Xeon||mPGA-603||CPU||400MHz||DDR / RDRAM|
|Pentium 4||Socket-478||CPU||400/533MHz||DDR / RDRAM|
|Athlon C/XP/MP||Socket-A||CPU||266/333MHz||133MHz / DDR|
|Pentium 4||Socket-423||CPU||400MHz||133MHz / RDRAM|
|Pentium III Tualatin||FC-PGA2||CPU||133MHz||133MHz|
|Duron, Athlon B||Socket-A||CPU||200MHz||133MHz|
|Athlon A||Slot-A||variable, <1/2 CPU||200MHz||133MHz|
|Pentium III EB||Slot-1, FC-PGA||CPU||133MHz||133MHz|
|Pentium III Xeon||Slot-2||CPU||100MHz||100MHz|
|Pentium III||Slot-1||1/2 CPU||100MHz||100MHz|
|Pentium II||Socket-7||1/2 CPU||66MHz||66MHz|
L2 cache speed refers to how fast the level-2 cache runs. All modern CPUs have a multi-level memory cache structure. Level-1 cache always runs at the same speed as the CPU, but it's small. Level-2 cache is larger, but may run slower - half the CPU speed or less.
FSB means front side bus - the main highway between the CPU and the rest of the system. The memory, PCI bus, AGP bus, all hook into the FSB. It runs at the same speed as the memory, except in the Athlon/Duron where it runs at 200MHz, and in the Pentium 4 where it runs at 400MHz.
And if that's not enough, here are some amazingly detailed tables from Tom's Hardware that show even more.
Some other notes:
When shopping for CPUs you may find you can buy either the OEM package or the retail package, and the OEM package is cheaper. So which should you get? The difference is that the retail package includes a heat sink and fan, while the OEM package does not. If you are going to buy a hopped-up aftermarket heat sink and fan, then of course you want the OEM package. If you don't care too much about the heat sink and fan, you might as well buy the retail package.