Computer on but no signal (making noises)

Hey guys, when I turn my computer on the lights go on, fans start and I get a beep, which usually happens when I turn my computer on. It takes a while about two or three minutes then my keyboard and mouse light up and I wait for my monitor to go on which does not happen. It says "no signal" when I manually turn my monitor on. I was using my computer half an hour ago but went out and turned it on as I left and came back, put it on and this happened. I tried moving my ram, running with only one stick. Cleaned all my fans/graphics card, removed and put my graphics card back. Took out the little battery thing for 5 minutes, put it back. I don't know what else to do. I manually built it in July last year and I'm an intense gamer. I use my computer every day and this has only happened now. Btw I'm a bit rusty on the old computer terms so can you assume you're talking to someone who doesn't know a lot. Any help is appreciated guys.