When you raise the System Bus (HTT), it in turn raises the speed of the CPU as well as the memory, since both of their speeds are derived from the System Bus. There is no way of overclocking your CPU and Memory seperately, however there is a way to set a ratio of your system bus and memory so that for every 6MHz of the HTT (System Bus) your memory runs at 5 MHz. So if your HTT is 240, and your CPU multiplier is at 10, and your memory is running on a 6:5 divider, then your Processor speed would be (240 x 10 = 2400MHz, 2.4GHz), and your memory speed would be (240 x5 /6 = 200Mhz) or in other words...stock speed.
As for the video card, that is totally seperate. For overclocking a video card, you literally more a bar left and right and then all you have to do is check for stability, lol.