I have seen many posts on DDR, and separately many posts on DDR2, but my question is a comparative of the two. I have a current Cyclone III design using DDR that I am thinking of moving to a Cyclone IV with DDR2. DDR2 (not related to the controller but rather the memory technology itself) has higher latency than DDR, which is a negative, but can be clocked twice as fast which would compensate to yield a much higher throughput…IF…the memory could be clocked that fast. My problem is that the Cyclone III-I7 device or Cyclone IV-I7 device cannot clock the memory faster than 167MHz and it’s a hard limit for DDR AND DDR2. So ultimately my question is as follows: Is there any memory performance advantage to DDR2 (over DDR) given the constraints of the HP controller which limits BOTH to 167MHz? I would think the DDR2 would actually be a little slower due to the added latency over DDR, given the same clock speed.
I definitely understand that DDR2 is faster if you’re clocking it twice as fast as a DDR device but if you’re using the Industrial speed grade devices, then the max clock rate to either device is the same (167MHz).
Am I missing something? (hopefully!)