They are alerts to tell you that your computer failed to post properly. funny that your computer boots and jut runs slowly. Any way the beeps tell you what particular hardware component is malfunctioning. Read your manual for the codded beep translation
Not sure about your particular mother board. from what i have read it is and indicator of video card problems, ram or possibly even hdd, depending on manufacturer. try replacing these parts with old ones you or a friend may have access to. if the problem goes away when swapped with a particular part then you have successfully diagnosed the problem and now know what you must replace.