Can someone please help me troubleshoot my old DFI AK76-SN Motherboard?

Ok. Here is the problem. It was running fine but not great so I switch to a newer power supply of the same watt power. While doing so, I must have brought my computer down from being upright to on its side. But after I tried turning on my computer which it did turn on. The screen gives me a No Signal Error. I've had that before and solved it a few times but this one just wont go away. I've tried switching out memory to see if that was the problem, disconnect everything and then reconnect everything save for the CPU fan and heatsink, And still get a No Signal Error. After that, I just removed everything to the basics: the RAM, Video Card, and Power Supply. Still get a No Signal Error. What is funny about this one is I know the motherboard still works because I have a pci lan card that has an led that comes on when power is supplied to it. And everything runs fine after being plugged back in. And still, I get a No Signal Error. I even switched back to the original power supply too. I've also tried clearing the CMOS a few times by Jumper Setting. Still No Signal error message on the screen. I've tried just about everything and this one has me stumped. Can anybody help?