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Memory Latency


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666 MHz means your memory cycle time is 1.5 ns, which equals to 1T. The memory chips are made of a matrix of cells, where there are a certain number of columns and rows. The 4 timing values represent the time your memory chips will take to access a row, a column, and then finally the actual data. The first 9 means CAS Latency = 9T = 9 x 1.5 ns in your case. The second 9 is for RCD, the third 9 is for RP, and the 24 is for RAS. It's quite a complex method, but you can read more about it at:

http://en.wikipedia.org/wiki/Memory_timings

Regards,

Fiery

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Thanks for your answer.

But, I know about the timings. It just that I'm not able to find any correlation to my measured value 71ns.

At first I think the real frequency the memory is working with is 166MHz. 666MHz is only from prefetching data.

But also using this value (1/166 = 6ns) could not explain where this 71ns come from.

So here some more details what I'd like to do:

I measured the memory latency and now, I want to find out, if that value is what to expect by using the manufacture informations.

Is this even possible?

Best regards

André Grimm

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Since there're several other factors (like memory controller's own latency), it's not possible to directly translate clocks+CL/RCD/RP/RAS timings into memory latency. Please note that clocks and CL/RCD/RP/RAS latency values are detected, while memory latency is measured.

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