I just recently solved an issue with my maching not starting up and it had to do with the USB port on the motherboard that was connected to my cases front USB ports.
I got some message about the USB device overheating and that the machine would shut down in 15 seconds. When I tried rebooting the machine basically died on me and I thought that the PSU fried. I decided to unplug the USB cables from my motherboard that were connected to the front ports on my tower and it "fixed" the problem.
I have a Cooler Master 690 II Advanced and I'm not exactly sure why this is happening. I'd love to use the ports on the front of my case, but I'm not going to worry if I can't solve this problem.
I think I may have bent some pins in the USB port (the ports on the CM 690 are crazy tight). Some sort of short? Could this cause the issue? Anyone else ever have this problem?
I used one of their tall cases a few years back when upgrading my mobo and had issues with LED and usb not working. The case ended up turning into a wonderful piece of scrap steel after about 9 months of trying to resolve too many issues with shorts. I stuck the mobo in an emachine's case and everything worked fine. robbed the barebones setup of the psu and fans (yeah, they make great fans) but that's about it.
The light on the on button never worked. the usb and front mic jack never worked. it was a Gigabyte am2 socket mobo that still works... piece of crap cases.