CL9-9-9-24 is the timings. Tighter the timings, the faster the ram is at accesssing the data that is on the it.
Anyway this is taken out of my wonderful newbie guide on overclocking (see sig)
There are 5 main timings in for RAM and they are the following:
tCL (CAS Latency) - 9
tRCD - 9
rRP - 9
rRAS - 24
Command Per Clock (CMD) - 2T
The best way I can describe each of these is to use the examples used in a MaximumPC magazine I got, which describes things as if they were a librarian going for row to row of books in a library >.>
“tRCD setting, for example, describes how much time the librarian has to get to a certain row on a shelving column. Set it too low, and she can't get to the row where your desired book is.
Say she reaches the row, tRAS determines the amount of time the librarian can linger there find your book.. tRP is how much time the librarian has to get from the row she was at to the bottom of the ladder.
TCL is how much time the librarian has to move from one shelf of books to a different one. Setting this too low is like asking her to move a 30-foot ladder 100 yrds in 2 seconds. TRAS is basically how much time overall the operation takes to climb the ladder, get your book and get off. CMD is the amount of time between one request and the next.”
Also see here as well for more info. I call it The Holy Grail of RAM