Originally Posted by robbyriverside
Thanks for the answer.
One of the reasons I selected that RAM is because the CAS was 7.
I know there is also row latency. Is that the latency you are referring to?
BTW I also noticed that the CAS went up from DDR to DDR2 and DDR3.
Seems to approximately double each step. Was never able to find a good explanation of that. Do you know of one?
Well the processor has a Tp Or timing processor value and ram has a Tc or timing critical value. These are AC or alternating current processes within the electronics as they change from the switched states of 1s and 0's. They don't go directly to charged or uncharged state and take a while to stabilize. Wait states are just time, speed is just time as they up the clock speed they up the wait states. 800 mhz ram at 5 wait states operates completely differently but exactly the same performance as 1600 mhz 10wait state ram. The changes in ram are so small a they progress to actually get the advantages out of them they have to increase speed to set the correct timings. For instance the ram changes might be so small that they can't just go 800mhz and 4 wait states but the ram is faster than 1600mhz and 10 wait states. So they go 1600mhz and 9 wait states. As you see it lets you get your small increases in speed out.
You either have to directly caluclate your Tc or compare it to see if the change is real or just math lies. Calculate the T cycle length from the clock speed and multiply it by wait states to get the actual Tc of the module or just compare... 1600mhz 9 wait states is 11 percent faster than 800mhz 5 wait states. 1/1600x9 compared to 1/800x5 come out to about 88.9 percent.
Row and column stuff doesn't really matter. They all have the same architechtures and yes you have huge hit in speed when you get out of your rows. But the huge hit is so huge it's buried under an avalange of time that clock speed doesn't have much affect on latency. When you go from 5 to 14 wait states or 7 to 23 wait states clock speed doesn't really matter as you are waiting way past several clock leading edges and trailing edges.
Latency is directly related to speed of the ram. If the ram is ready to be read your initial access is much faster with faster clocked ram. But doesn't really matter under any real world situation. Think of it as the same as hard drive rpm. Higher RPM will have lower latency because once the read is resolved the drive has to wait less time for the platter to rotate under the read head.