有關CPU North Frequency

CPU North Frequency=外頻x 一個倍數.
但這個倍數係受什麼限制?
CPU, MB?
如以下amd PII 810 + AMD770. 10x 倍數,點解最後超到240 唔係 =2400 得2100?
http://www.cpu3d.com/review/7715 ... d/introduction.html
個倍數係唔係張張板唔到? 有無D 11x,12x?
聽說高CPU North Frequency比超其他的好.