Memory timing? Buffered and unbuffered?

[M0ddingMan1a]

so wat is up with all that? like for instance:
http://www.newegg.com/Product/Product.asp?Item=N82E16820145450
^ this sets timing is 2-3-3-6
http://www.newegg.com/Product/Product.asp?Item=N82E16820145492
^ and this one is 3-3-3-8

so wat is that and how does it make a difference? and also, wats the difference with buffered RAM and unbuffered ones?

EDIT: o yea, and wat is 'cas latency'?

 

[Cromewell]

RAM 101

 

[H_L]

101 still doesn’t tell you much about the timing and what 3-3-3-8 means, what does the numbers refer to? cell seek time <-- in clock cycles?

 

[Cromewell]

It says right here:

Timings are usually listed something like 2-2-2-6-1 or 1-6-2-2-2. What the numbers stand for are CAS-tRC-tRP-tRAS-CMD

1. tRAS Active Precharge Delay, this is the delay between a command being received (from the memory controller) and firing up the RAS.
2. tRP [o]RAS Precharge[/i]. Memory is stored in a gridlike array and at the end of every row (memory is searched cell by cell), there is a delay associated with "moving to the next row".
3. tRCD RAS to CAS Delay: memory is stored in a gridlike array and this latency represents the time that must pass between locating the row and then starting to look for the column.
4. CAS. Column Acces Strobe, this number represents the number of cycles that must pass before the memory can locate the exact hex addresss of the memory cell required.
5. CMD Command Rate is the delay time associated with locating which bank of memory to search through (this explains why having say, four DIMMs usually results in CMD-2T: a lot more virtual memory locations need to be searched through to translate to a physical location for further searching)
This page has a look at the advantages of tweaking each individual timing