I'm assuming bip is a "beep". If that's the case a continuous beep could be any number of things. I would actually first look at the keyboard/mouse and/or controller before going for the CMOS battery. Try disconnecting the keyboard and mouse from the computer and turn it on. If no beep occurs it's likely an issue with the keyboard, try replacing it.
If the beep still occurs after disconnecting the keyboard and mouse it's possible it could be a CMOS setting causing the issue, connect the keyboard back into the computer and enter CMOS setup and try restoring the default settings.
Information about getting into CMOS:
http://www.computerhope.com/issues/ch000192.htmIf issues still occur you may want to try replacing it as patio suggested above. However, it's also very likely a keyboard controller on the motherboard. If the CMOS battery does not resolve the issue unfortunately you'd need to replace the motherboard to fix the issue.
Usually beep codes are several beeps and not a continuous beep (beep more than 3 sec). However, additional information about beep codes can be found on the below page.
http://www.computerhope.com/beep.htmIf nothing is done I wouldn't imagine it would cause any harm to your computer other than possibly not being able to keep time if the issue is really a CMOS battery.
