Hi. My HP Pavilion Desktop wont boot. It is stock at the HP Logo and I can hear a beeping sound from the PSU not from the motherboard. I just replaced the 300W PSU to a new 600W PSU but the beeping sound still remains and still at frozen HP logo at startup. I already tried cleaning and re-inserting all wires and memory modules but still has the problem. What else could be wrong? What does the beep sound from the PSU means? Thank you.