If your FSB is 133 by default your PCI bus (sound, network, hard disks etc) is at 1/4 = 33MHz
The AGP bus (Video card) is at 1/2 =66MHz
As you increase the FSB, the PCI and AGP buses will be overclocked. Ie at 150MHz: PCI=37.5MHz, AGP=75MHz.
This can cause wear and tear, but as 'ThePunkGeek' says, take it slowly. Increase the FSB about 1 or 2MHz at a time and try running
[email protected] (see the
[email protected] forum) or 3dmark2001 se (
www.madonion.com) for a few hours to see if the system is stable.
Often, to increase stability (ie if your PC crashes after a few minutes) you can increase the CPU voltage. For Thunderbirds the default is 1.75Volts - increase this to about 1.8 to 1.85Volts for better stablity. This will also result in higher case temperatures - make sure that you have a good CPU fan and heatsink and a few good case fans.