No signal form PC! Help!

Just put in a new PSU and now, none of the video card outputs are displaying a video signal (but there is no signal through the on board meaning its being sent through the card right?). During instillation, i did take out the RAM cards since they were in the way buy they are definitely in correctly now. When I turn on the computer, all fans run and everything lights up correctly, just no video.... I have yet to reseat the card which I'm about to do but could there be anything very wrong that could be done during a SPU installation causing the problem? Thanks!

GC not fully inserted. RAM not fullt seated. All power cables not connected.

After checking that and pc still does not boot, remove all ram and try to boot. If pc emits long bips, it means that you have one or more stick of ram deffective.

thanks man, it was the ram. I didn't figure it out myself though. I had to take it to geek squad who reconized that the motherboard I have is a **** to insert RAM into. It took each of us some strong force to push the cards in but after it worked. Thanks for the input!