1) Initially, the computer would turn on. All the fans and stuff would turn on, but the main power light and the "hard disk activity" light will not turn on. However, the floppy drive will light up. I do not think the processor is running, as I am not detecting any change in heat near the heatsink.
2) After messing around a bit with the "Power LED", "HDD LED," and "PWR SW" wires, I have managed to get the main power light (where the button to turn on the computer is) to turn on. However, I still see nothing from the monitor, and the HD-Activity light is still dead. However, when I turn the computer off, the HD-activity light will turn on and remain solid.
3) I tried taking out the AGP video card and connecting the monitor directly to the motherboard. I know that my old video card was broken, but the new one (my current one) works fine when installed into the other mobo. Either way, the monitor continues to display "No Signal" no matter how I connect it to the computer (video card or mobo).
The motherboard I'm trying to install now is actually the older motherboard that came with the computer when I bought it a few years ago. I tried changing mobos a little while ago, as I thought that it was broken (it turned out to be the video card). However, due to weird problems that keep popping up, I'm trying to switch back to the original mobo (I'll call it Mobo A from now on). I'm fairly sure Mobo A works, as it was the original mobo to begin with.
If anyone has any ideas, please offer some help. This is my first time installing a motherboard by myself, and I did most of the installation based off of reference pictures of an already installed motherboard.