Hmm just came across this (albeit a tad old info):
"Command Rate: Also called CPC (Command Per Clock). The amount of time in cycles when the chip select is executed and the commands can be issued. The lower (1T) the faster the performance, but 2T is used to maintain system stability. On Intel based machines, 1T is always used where the number of banks per channel are limited to 4. Most intel based motherboards don't cooperate well with 1t command rates even if the memory module is able to support it. Most times it will produce memory corruptions (especially with overclocking) which results in very poor performance."
"It makes a meaningful difference in memory related benchmarks. In daily use... not so much."