Honored Contributor
Honored ContributorI have explained the math behind saturating memory bandwidth here (http://www.alteraforum.com/forum/showthread.php?t=57099&p=232613#post232613). An unroll factor of 32 is likely more than enough to fully saturate the memory bandwidth. Anything more than that will result in a lot of memory contention and lowered performance. You are losing performance due to two reasons: lowered operating frequency, and lowered memory bandwidth due to higher amount of contention. Trying to decipher the numbers reported by the profiler generally results in more confusion, and I have encountered many cases in which the numbers simply do not make sense and contradict each other or the timing results. My recommendation is not to rely too much on those numbers.
