If your system will not boot up and is sounding a series of BIOS beep codes, the motherboard's manual may help you determine what the problem is. There will be one long and a series of short beeps. The number of short beeps would be used to determine which code is being reported. Refer to the motherboard manual for the meaning of each code.
Sometimes a bad add-on card can cause problems. If beep codes are not generated when all other expansion cards are absent, one of the add-in cards is causing the malfunction. Insert the cards back into the system one at a time until the problem happens again. This will reveal the malfunctioning card.