Beeping noises after startup are usually a sign of hardware related issues or an indication of high temperatures. When was the last time you cleaned the inside of your computer? Open your machine and make sure the fans are working and the heat sink on the processor is not blocked with dust or debris. Remove the CPU's cooling unit and clean the fins on the heat sink that sits under the CPU with a can of compressed air. Dust restricts the airflow and prevents proper cooling. You can also remove the cards, RAM modules, clean the contacts and reseat them. Check your connections and fans to make sure they are working properly and monitor the temperature.
When a computer is first turned on or rebooted, its BIOS performs a power-on self test (POST) to test the system's hardware. The BIOS checks to make sure that all of the system's hardware components are working properly and that it meets the necessary system requirements before booting up. If BIOS detects an error and fails the POST, the computer returns a pattern of beeps indicating what is causing the problem.
Beep codes can be in several different patterns, depending on the BIOS that you are using. Some BIOSes use simple beep codes in a pattern of varying numbers of short beeps, while others may mix short and long beeps. The exact meaning of the beep codes depends on the type and version of BIOS that you have. The three most popular types of BIOS are those made by Award, American Megatrends (AMI) and Phoenix.
In order to interpret the beep code pattern you are receiving you need to know exactly what version of BIOS your computer has. The easiest way to do this is to download and install the Belarc Advisor from here
. After installed, run the Advisor and it will produce a report with the version of BIOS on your computer. Then you can look up the appropriate codes for the manufacturer at BIOS Central