I'm sorry I wasn't clear enough, because it's not a jumper to change the FSB. Here's a picture of the jumpersettings in the manual. picture
As you can see, it goes from 16x to 24x. So in theory, it would be possible to use a 2,4Ghz (18 x 133), choose an FSB of 133 (another jumper) and select a 24x multi, which would run the CPU at 3,2Ghz on a 133Mhz bus. Somehow I doubt this is possible
But this brings me back to my initial question; why that jumper?