AMD's model numbers are comparable to P4 clock speed, so a 3000+ is equivilent to 3.0GHz P4, 3200+ is equivilent to 3.2GHz, etc
I didn't mention the 4000+ because of it's price - $334. That's $100 more for a mere 200MHz more clock speed...definitely not worth it.
A64 multipliers are "half locked"...that means you can lower them, but you can't raise them higher than the default. Generally, lowering them is what you wanna do anyway...that means you can raise the FSB without over-overclocking the CPU, & FSB is where the performance is. However, overclocking an A64 is more complicated than overclcoking a P4 or Athlon XP. The thing about the A64 is that it doesn't actually use a FSB, it uses a HyperTransport bus, which on the S939 runs at 1000MHz (2000MHz effective). The CPU has a base frequency setting of 200MHz & an HT multiplier of 5, but these can both be adjusted, along with the CPU multiplier.
Just as an example, let's say your CPU runs at 2200MHz (11 x 200MHz). You could raise the CPU frequency to 250MHz, lower the CPU multiplier to 10x...that would give you a CPU speed of 2500MHz, but you'd also have to lower the HT multipler to 4x to bring the HTT bus down to 1000MHz (250 x 4). But you'd still have memory settings to contend with as well.
Maybe these will help explain:
http://www.madshrimps.be/?action=gethowto&howtoID=58
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2548&p=3
ASUS A7N8X-X
Athlon XP 1800+
8.5 x 200MHz
1024MB PC3200 2.5-3-3-7
Asus A9550GE/TD 128MB
WinME/WinXP Pro SP2
