It sounds like a card isn't seated well, a power cord isn't seated well or something is shorting a component. It also sounds like you've already been going thru the Boot-no-video troubleshooting guide from the Homebuilt section: http://www.tomshardware.com/forum/261145-31-perform-ste... I think you need to do a thorough Breadboard on the system: http://www.tomshardware.co.uk/forum/page-262730_13_0.ht... Completely remove all components from the case. I use a large wooden cutting board to set all the components on but some phone books will do just fine. Start out with minimal components: mobo, CPU, one stick of RAM, monitor keyboard and mouse. Make sure all the power cables are properly seated....in my opinion the most likely issue is you're either shorting components in the case or not properly seating the power cables and i'm leaning towrds the 24pin cable.