Hi there, welcome to the forums.
I know you said you troubleshooted, but I'll go ahead and link this thread: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-boot-video-problems
Look through and follow what you havent done.
To me, it sounds like a display issue. Have you checked the monitor? I was in the same situation you were for a while, and it turned out it was my monitor.
Let me know what the guide turns up!