I'm trying to undo and overclock on my computer my brother?

Did a few years ago.. I done some reading on overclocking and when I went to the bios then clicked on advance chipset configuration there was no option to change the fsb frequency or cpu clock ratio.. The only options there were was memory frequency which gave me 3 options 400ghz 600ghz or 900ghz and 4 other options that started with sdram or something I can't remember.... Any ideas how I can turn down the overclock?? My fan is very noisy when I run programs...