ClockGen is an program dedicated to overclocking. Its main purpose is to change the system clocks on the fly : FSB (Front Side Bus) and GSB (Graphic Side Bus). ClockGen also provides some functions that allow you to improve and monitor your overclock.
If your mainboard does not appear in the list or if you can't open your system, you can try to guess the clock generator family with the chipset. Most PLL models are dedicated to a chipset, and knowing the chipset may help to figure out the PLL model family, especially on ICS chips. On ICS chips with a 6 figures name, the model consists in the 4 first figures. For example, the ICS 954148 belongs to the 9541XX family. The following table may help you figuring out what PLL family your system uses.