If by "everything else" you mean the RAM and the graphics card, then no.
Normally the speed of the RAM matches the HTT, so in that sense, changing the speed of the CPU changes the speed of the RAM also (unless all you change is the multiplier, in which case the CPU speed would change and the RAM speed would be untouched), but you can set up a divider so that the ratio of the RAM speed to the HTT is something other than 1:1. So most of the time you can overclock your processor and still keep your RAM at about stock speeds.
Overclocking the graphics card is done with software and is unrelated to what you do with your CPU/RAM - for instance, my motherboard has no overclocking options, but I've still overclocked my video card with RivaTuner.
Hopefully all of that is correct!