Quote Originally Posted by xMrBunglex View Post
obviously, those all represent a 1:2 ratio. i think 200, 266, 333, and 400 are the different boot straps. the lower, the quicker.
Correct. The reference frequency tells the MCH what speed it should assume it's running at and to set its internal timings appropriately. The lower it's set, the lower the MCH latencies. Just like memory, there's a tradeoff between latency, speed, and voltage.