Well, I bought a new computer case for my computer today, and after moving all the components over, the computer won't turn on. I was able to jump the PSU with a paper clip, and all the components and fans turned on fine, including the CPU fan which, of course, is powered through the Mobo, but it won't turn on by itself.
I have tried switching the power and reset switch connections on the mobo to see if maybe it was the power button with no luck. I have tried unplugging everything with the exception of the CPU assembly, RAM, and PSU, no luck. I even tried taking the RAM out one stick at a time, no luck.
All components are fairly new, the motherboard being about 8 months old, and the PSU even newer. I was pretty careful when taking them out of the old case, using antistatic bags and such.
I do notice a highish pitched electrical noise coming from the motherboard when the power supply is plugged in.
Update: Still messing with it. I ended up taking the mobo and PSU out and putting em back in the other case, and it still wouldn't turn on. I then took a paperclip and touched the two pins on the mobo that the power button connects to, and it actually turned on. After that, I plugged the button back in, and it was able to turn on and off with the button. I then moved the mobo and psu back to the new case, and the button was working. I figured whatever had happened was fixed, plugged all the components back in, and now it won't turn on again. Even touching the pins with a paper clip isn't doing it. No idea what is going on.