socrates777 -
As noted by sumdumguy above, look on the motherboard itself for the manufacturer, model and revision numbers. They are sometimes printed along the edges of the board - many times in white lettering. DO check your connections as suggested by nihil and you might try reseating your graphics card as well as your RAM. I've saved myself a lot of time by reseating RAM or a graphics card . . . before stripping a system down to the bare minimum to try and determine the problem area. The problem you describe is one I've become all too familiar with (no monitor display and non-responsive power supply) and 9 times out of 10 was linked to a memory module that had gone bad or which was not securely seated. I'm sure you know this already but, remember to turn off and unplug your power supply before opening up the case . . . otherwise a bad graphics card or RAM stick will be the least of your problems.

V.