It's not without reason. The CPU simply throttles back to a X6 multiplier when it's under a low load. I don't particularly care about the power saving aspects, but it helps cut down on the amount of heat generated inside the case. If it bothers you, go into the BIOS and turn it off. Generally, you can find it in the "Advanced Features" menu.
so can you tell me what soft of setting that i should turn it off? am not very familiar with bios but i can recognized it if you could give me the similar setting
okay i'll try to find out then..thanks