Crystals are like 30 year old technology. Today, the clock frequency for the motherboard comes from an oscillator.
Anyway, if you are looking to change the settings, you need to get into your BIOS. Doing that is not exactly straightforward as every manufacturer does it differently. Generally, there is a key that you press during the POST. Could be <esc> or any of the F-keys. Even then, if you have a graphical screen during post, you have to disable that so that you see the text during post to get to that point, which again is one of the above keys. Watch your boot screen carefully when you power on and you should get the specific instruction (but it will not be on screen for very long).
Then you need to know your way around the BIOS. If you can get the specific model of your motherboard, you can DL a manual from the manufacturer. Actually, that should also tell you how to get into the BIOS in the first place so do that before anything else.
Keep a notebook handy and write down any settings before making changes or you could end up locked out of your computer.
The motherboard frequency is generally called FSB or Front Side Bus. The CPU multiplier is what it is.
I find it helps to have a second computer nearby running a spread sheet. I put the allowable FSB settings in rows and the CPU multiplier setting in the odd numbered columns, with the even numbered columns for any notes that I want to make.
Also, set your FSB to about half what it defaults to when you are playing with multipliers and your multiplier to half way when changing the FSB.
If you want to get into hard core overclocking, there is a good deal more to this to deal with but that is enough to probe your basic settings.