DDR ?-?-? 2100,2700,3200,.... so many numbers!??!

[Flakk]

What do those 3 or 4 numbers refer to that are often displayed with a dash inbtween after the ram's name? Something about latencies or ram timings as far as I can gather.. can anyone clear that up for me? Any additional info on why they are good or what to look for, and brands that are good would be nice too

 

[nick1985]

latencies are all that matters. a 2:2:2 latency 2100 will beat a 2.5:3:3 3200

 

[Flakk]

2-2-2 2100 will beat it for access speed but the 2.5-3-3 3200 will still have a higher max amount of data per second wont it? what are each of those numbers??? different levels of latency or something?

 

[THUGSROOK]

hi flakk

pc1600 = 100/200ddr
pc2100 = 133/266ddr
pc2700 = 166/333ddr
pc3000 = 180/360ddr
pc3200 = 200/400ddr
pc3500 = 216/433ddr

PC is just a fancy fat number for ddr that also shows its potential bandwidth,

HTH

 

[Flakk]

hey thugs, yeah that part is the part i get.. it's the latencies that i dont fully understand

 

[THUGSROOK]

oh um ok, cas latencies...

..are like delay periods.
cas2-2-2-5 could be said to have a total of 11 delay periods, where as cas2.5-3-3-7 has a total of 15.5 delay periods and will be slower ~ the lower the number of delay periods the faster the ram & system.

HTH

 

[Flakk]

hrm okie... interesting

how come usually the later numbers are higher than the first ones.. like 2-2-3-5 or something

and sometimes i see one where the 3rd number is higher but the last one is less (i think)... if anyone knowledgable would care to enlighten me, how does that all work

 

[THUGSROOK]

the arrangement depends on the moboard ~ they mean the same, just in a different order.

 

[canadianpsycho]

Originally posted by: nick1985
latencies are all that matters. a 2:2:2 latency 2100 will beat a 2.5:3:3 3200

Not if you're running a p4 setup. Bandwidth > latency when it comes to intel CPUS.

 

[MIDIman]

so again - in a P4 setup (overclocking a 1.6a on 845e chipset / bd7-II):

1) Would ram at 133/266 cas2-2-2-5 be faster or slower than the same ram at 166/333 cas2.5-3-3-6?
2) Would the answer differ for an AMD setup (kt266a)?

also another question that can be valid here:

3) How can i do the math for the 2:3 cpu:ram ratio before actually trying to boot.