Don't overclock the CPU and you will get your ram speeds returned.
I know that. My question was whether or not the RAM at 1140 MHz would bottleneck my system if I were to get a 7970. My other question was if it is worth it to upgrade to 2133 RAM to run at ~1800 MHz given the same worst-case scenario underclock. Again, this is a question about value; a 3 FPS increase does not matter to me, but a 10 FPS increase might.