How can beep sounds point out complaints in a motherboard?

the meanin of the beeps can be found in the manual, and it can help you troubleshoot the hardware, or for example a beep that tells you the memory is bad. if you can’t find the manual you could google for it.

The Beeps are called “POST Beeps” – POST stands for “Power On Self Test”.

The exact combination of beeps used varies from one kind of hardware to another. Wikipedia has links to the most commonly-used codes here: http://en.wikipedia.org/wiki/Power-on_self-test