Computer running but no signal.

Hello.

I have been having this issue for a long time now. Sometimes when I turn my desktop computer off, the next time I turn it on everything seems like it is running but I get no signal on my monitor.
When I first had this issue I thought it was the VGA cable but that was not it. I found out later that if I took the battery out of the motherboard, wiped it then put it back in my pc would work.
I have been doing this for about a year now... but today I am having the same issue and I don't know what to do.