Asus A8N-E

This board has been working fine for 2 years. Recently, started having probs such as machine was running slow, then the machine crashed. I then checked everything and no luck just a continuous beeping so you would get beeeeep then the next beeeep going on forever. So replaced the board with a winfast nf4k8ac brand new board. Ran this and I got continuous beeping so you would get beeeeep then the next beeeep going on forever. No video either. So I reinstalled the old asus board, and it worked and was fine that evening, did a whole lot of upgrades, until 2 in the morning. Worked great. Next day went to switch it on and I got the same beeping I had on the Winfast board and screen saying no video. So I have disconnected everything except the ps, cpu and fans and still the same beeping. Fans spin. Any ideas?