Newbie Memory Question

I've been reading these boards extensively for a few weeks and I am getting quite the education. The community here is an impressive resource.

One bit of info I haven't been able to find is regarding memory timing. Memory timing is speced in four numbers, the first being cas latency, which generally is 2, 2.5 or 3 (DDR 400 pc 3200). What do the other three numbers reference? I was told the only number I really needed to worry about was the latency, but I'm curious.

Thanks,

Bob

DDR if I remember correctly stands for Duel Dynamic Redundency which means the memory will run two cycles for every clock cycle when in DDR mode. The 400 refers to the hertz (or frequency) the memory runs at. PC3200 means the bandwidth of the memory. CL refers to how many times the memory refreshes itself for each cycle.

CL is almost never referred to anymore in newer memory sticks.

There is even a DDR2 out now.

As a rule of thumb, when buying DDR memory, buy the same brand in pairs of two.
i.e. two sticks of 512MB. Make sure your motherboard accepts that particular brand. Some motherboards can be very picky, so RTFM. Asus is notorious for being picky.
Some brands and models of memory like kingston hyper-X run at slightly different voltages than stock settings on motherboards have. They won't work unless you adjust the voltage in BIOS. MSI brand motherboards will tell you this. Again, RTFM.

Don't buy cheapo memory. You get what you pay for. Stick with well known major brands like Kingston, Crucial, Corsair etc....

Memory will run as fast as the slowest stick on your system. So if you have PC2700 and PC3200 in your system it will run at PC2700 speed and if I'm not mistaken, non-DDR mode.

Putting faster memory than your motherboard will accept is a waste of money. Either it won't work, or you'll run at the fastest speed your motherboard can run.