I have a HP Pavilion p6680t CTO Desktop PC, brought brand new around 2012 from HP. Haven’t done any upgrade at all. Haven’t used it in the last few months. Turned on today, no video signal to the monitor, keyboard doesn’t seem to work (pressed num lock and cap lock, lights didn’t come on). Tried the video cable and monitor on another computer, they both work fine. The CPU and power supply fans are working. The lights on the PC comes on as usual. Any suggestion?