heres something interesting from:
http://burks.bton.ac.uk/burks/pcinfo/hardware/bios_sg/bios_sg.htm
"How do I clear the BIOS memory?
Three alternatives are available depending of your type of motherboard:
Enter BIOS Setup and change to settings to Power-On Defaults.
Disconnect the battery.
Insert appropriate jumper an wait until the BIOS memory is cleared (see mainboard documentation, the jumper is often located near the battery).
Sometimes this is possible with DIP switches on the motherboard. Sometimes (if not), you will have to remove the battery. And sometimes (if no DIP's and no removable battery, and not willing to desolder the battery), you can short the battery with a resistor to lower the current available for the CMOS.
This is only recommendable as a very last option. The NiCad cells often employed have a very low internal resistance, so the resistor will have to be of a very low value for the voltage to drop significantly. The corresponding current would be quite high, which is not very good for battery life. A better option would be to use a resistor to discharge the battery. Obviously, this only makes sense when you have a NiCad cell (which will be recharged every time you turn the computer on) as opposed to a lithium cell (which cannot be recharged). In the former case, a resistor of 39 Ohm will discharge the battery in under half an hour relatively safely.
Another good way to discharge the NiCad is to put a 6 volt lantern lamp across it, and let it discharge completely. Not only does it provide an effective load, it also gives a visual indication of the charge state. It's a good way to prevent "ghost memory" that's so common to NiCads. Metal Nickel Hydride batteries are now being seen in some systems. They don't have this problem and they are more $$. "