I'm not familiar with your mobo, but very often some parts of the BIOS settings are greyed out because some automatic, preset or optimal settings are selected elsewhere, and those greyed out portions can be made active by selecting manual settings.
For instance, if you choose 'Auto' for hard disk settings, details of the hard disk like number of cylinders, address mode, etc may be visible but greyed out. You can change those if you select the manual option.
This is often the case with RAM timings, clock speed, multiplier etc etc. The manual option may not be termed 'Manual', but something like 'Expert' or 'Aggressive' or something similar.