No monitor signal on boot

Hello. I've been having some trouble lately with my computer, it started few months back when my computer stopped giving monitor signal on boot. It worked very randomly and so I stopped turning off my pc. Had like 2 months uptime when I had to turn it off for some reason today. I was a bit afraid that the problem would come back, and it certainly did. I've been trying to get it to boot properly for half a day now, tried everything from stripping down to just necessary parts, powercycling, different monitors, prettymuch everything I could think of. Still no luck. It boots normally, leds and fans go on, everything seems fine but monitors stay blank. Any advice is more than welcome, please. Its pretty much my life in that machine there