RAM latency.....

[Beno]

Can someone explain in simplest English the RAM latency principle?

For example - I was looking at Corsair XMS 1GB DDR 400, PC3200 ECC Registered and it's latency is 3-3-3-8
Same brand, same specs but 512MB has a 2-2-2-5 latency - would there be any noticeable performance difference between the two?


cheers

Beno

[gipper51]

I'm not sure of all the technical stuff, but latency is basically how many cycles it takes for the processor to fully access the memory. The CAS "Column Addressing Strobe" latency refers to the data columns located on the memory. I don't know what all the number in the timing ratings mean, but the first number is usually the most important and tells you the clock cycles required. The lower the better, and the RAM with the 2-2-2-5 timing will take 2 cycles for the CPU to access the RAM, where the 3-3-3-8 takes 3. Most of the cheaper RAM has ratings of either 2.5 or 3 cycles and the more expensive RAM is rated at 2, but for some reason they can only get timings down to 3 for 1GB sticks. I don't think you'll see much difference between the two sticks. I'm sure the difference can be measured but you won't notice in your day-to-day workflow I wouldn't think.

Gipper