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Altera_Forum
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15 years ago

Calculating speed of DDR2-RAM using DDR2-HPC

Hello, i've got a question about calculating speed of DDR2-RAM using DDR2-HPC from Altera. I'm using CycloneIII-Dev-Board and know, that the maximum theoretical speed of DDR2 is: 167 MHz...
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Altera_Forum
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15 years ago

Latency is not the same as efficiency.

Your commands are pipelined so best case you could get close to 24Gbps but when the DDR2 needs to do a refresh and you're stuck waiting. So the overall speed or efficiency comes down to what read/write ratios and patterns you are using and what addressing patterns you are accessing (sequential or random?).

Its a fairly complex calculation and I am not sure Altera can provide an exact answer for your system. I'd perhaps look more at a memory vendor for this sort of information.