To clear the cmos you would move the jumper at the "cmos clr" block which is abbreviated for "cmos clearing". First you have to remove the battery on most as a requirement and then it over one pin for a few seconds only. Make sure you return that to the default position after this is done then replace the battery. Be careful about the battery holder. Some of those are a little pain in the .... to avoid bending the contacts or other damage to board. If you can't get it out by pressing down on one edge lightly tto have it pop up you will probably need a small pair of tweezers or screw driver to press a side of the holder enough to see the battery lift up. Once you have cleared the cmos the battery will drop right back easily with no hassles.
When the cmos is cleared everything will be at the factory defaults which means entering time and date, selecting OS2, changing the PCI default setting to AGP for the graphics, and deciding on the boot order since floppy is usually listed as the first if not the removable. On newer board you will see removable there. Don't move the other jumpers seen on the board without first being instructed by tech support or a techical document on the board for changing hardware configurations. You are clearing the cmos to see if that restores the correct memory timings and recognises the cpu as a 2400+. Look for the memory timings settings to see what it is at and adjust to the highest setting. If the front side bus is 333mhz you would set the timings to 166mhz in the bios, 133mhz for a 266mhz fsb there. If you then see the correct cpu model listed after saving and existing the bios with a restart there and everything runs normal you should be set. But if you start seeing Windows lock while booting or just reaching the desktop that would indicate the bios itself is failing then.