For the hell of it, Disconnect EVERYTHING remove ALL cards and try a full reassembly(I do not think you need to remove the cpu or cooler, but everything else).
Try the most simple boot you can with all non needed things removed(HDD/ODD/USB devices, just leave the keyboard). The goal is to see if it will post at least.
This is a guide to post related issues. All very basic, but may be worth a quick check.http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems
If all fails, You may have to test each part on a known good system. So it may be time to call in some favors with friends