Carefully inspect the motherboard. Perhaps a loudspeaker in miniature design for it already there. It has approximately the same diameter as a penny coin, and a black body. If you can't find it, try running the machine without attaching to the motherboard's external speaker. With such dynamics you will hear during the automatic equipment check (POST - Power-On Self-Test) single beep.
If it turned out that the built-in speaker on the motherboard is missing, first try to find a large speaker inside your computer's casing. Sometimes it is not visible for the reason that it's hidden between the metal front wall of the housing and the plastic false panels. But in any case, attached two wire cable with connector on the end. This connector is usually written Speaker.
It happens so that the connectors are not signed. In this case, locate the cable with a wide four-pin connector to the motherboard is not connected. Wire must be suitable both to his first and last contacts and the average must be unconnected, or may be absent altogether. Take an ordinary battery 1.5 V. Insert the first and last socket on the pin and connect them to the battery. If when you connect and disconnect you will hear the clicks, then this is the speaker connector. Do not touch with contacts not to obtain the strike voltage of self-inductance (speaker - inductive element). Then remove the pins.
Locate on the motherboard a combination of pins, designated as Speaker or SPKR. There should be also four. To them and connect (on the dead car) the speaker connector in either polarity.
Start the computer, after which during the passage of the POST make sure that the speaker earned the right. Run any program using it.