Hi there,
1 high pitch followed by a low pitch, could mean CPU overheating, not seated properly or on its way out, malfunctioning in some way.
If you get a single high pitch repeating over & over there is something extremely wrong with your CPU & you should switch your computer off immediately.
On my beep chart 6 short beeps say its a keyboard controller Gate A20 error, which could mean you mobo is stuffed or faulty keyboard.
Try removing all components clean out any dust etc, also remove the CMOS battery while doing this, when finished replace all components plus battery & restart system.
Hope this helps.
Ben.