I've got a similar situation...I think what you mean is that you get no graphics, but the fans,etc. seem to be working properly.
If my monitor is unconnected, I get an inquiry as to whether proper connection is done. But, if the monitor is connected to the video card/chip (with the system power off), I just get an amber light on the monitor. When I start the system, this amber light remains as it was.
I don't have an answer, but I tend to suspect that it's a motherboard problem...since I have tested a known good video card from one system in the troubled system (new motherboard, reliable PS). I have moved all of the components (RAM, PS, drives, video card) to other systems and they work satisfactorily there. This motherboard also has onboard video, a signal is generated to the monitor (as opposed to the monitor being unconnected) but the signal is not strong enough to trigger .
I am perplexed, maybe we can both learn something from this
One of the things you can check...if onboard video does not apply...is the seating of the video card. You can also check the connections of monitor and video chip/card.