You start out with 'any' monitor but then you only talk about one monitor.
Have you tried another monitor?
Replace the bios battery.
We recently moved and I just went to go turn my desktop only only to be greeted with a message on my monitor "No Signal". First thing I did was re start the computer and still nothing. The fans run and there is no beeping and the tower it's self boots up just like it normally does. I have checked all the power cords, DVI, VGA, and even opened the case and check to see if any of the wires had come loose in the move but still nothing. I have had this set up for years now and it has never given me problems before so I am at a loss. It is an HP Pavilion p6715f with an MS-7613 motherboard, Intel Core i3 550 Processor, a Corsair CX500 power supply, and an AMD XFX Radeon R7 260X graphics card.