Possible values of an option:
Depend on motherboard model, there can be a variant [Default] or [Auto]
The option description:
Defines frequencies of the system tyre and tyre AGP for synchronous chipsets (chipsets at which frequencies of all tyres are rigidly connected with each other). In this case the increase in frequency of the system tyre inevitably involves also growth of frequency of tyre AGP that can negatively affect stability of work of a video card, therefore at dispersal it is necessary to show the raised care.
Regular frequency of the system tyre depends on processor model, tyre AGP by default works on frequency of 66 MHz (66.67 MHz if to be more exact). If among possible values of an option there is a variant [Default] or [Auto], it corresponds to nominal frequencies of all tyres.