Help on Award BIOS & ASUS MOBO

Need some help on a puzzling problem. ASUS support has not been helpful.
I have an ASUS CUV4X-D MB, Award BIOS, dual PIII 1GHZ, 4x512MB Corsair DRAMM, GEForce2 GTS Video, IWin mini tower with 300w power supply.
I get a continous series of loud, low pitch beeps at intermittent times after boot up. Boot sequence is fine, single high pitch, POST shows OK. Go into BIOS, set for jumper free processor selection, reboot, everything OK. Start working on HDD and loading OS, computer starts beeping. Reboot, check CPU & MB temperatures, everything is within range. Disable all temperature and voltage checks on the BIOS, reboot, after some time, it starts beeping again. Tried different DRam, one stick at a time, different processors, still same beeps. Took out all ram, the beep is different, less loud and higher pitch.
Changed out the MB, still same problem.
I noticed the MB has what appears to be a built in speaker, just above the floppy controller. I am hooking up a piezo-electric speaker from the case to the speaker connections on the MB, as per the manual. Could this be the problem??? Bad case speaker?? But why does it start at different times??
Any suggestions or ideas would be very helpful...