My brother has the exact same problem while mine is working fine. He actually plugged the HDMI cable in and had this problem going.
He said it was fine earlier on before he changed the monitor :
Firstly he bought a monitor which does not support HDMI ( CPU working fine)
Secondly, came home plugged in HDMI ( 5 beeping sounds)
I searched online and bumped into forums saying that HDMI doesn't work.
I plugged out the HDMI cable, connect via DVI it worked again, perfectly.