If the support does not exist in the hardware, the feature cannot
be added by the BIOS. To lock the PCI and AGP bus, requires a
separate clock signal from the clock generator chip, and requires
resynchronization logic be added to the chipset. Via has a poor
track record of supporting this feature, even on current chipsets.
If you want PCI/AGP lock, download the manual for the board you
want to buy, and see if the AGP clock is programmable. But, also
read some reviews, because some BIOS have the settings for locking
AGP, but they don't actually work.
Paul