I've had a DVD drive in my computer that wasn't connected to the Motherboard because I didn't have a SATA cable. Just today I got one from the IT guy at work and plugged it in, now I have the problem I just described in the title.
Furthermore it only turns on the time I press the power button after plugging in the power cable, never any other time. When it turns on the fans spin, the blue lights all over my computer light up, then in less then a second it stops. I hope I haven't fried anything in the computer particularly since I was pretty proud of how quickly I put it in, I'm usually pretty damn clumsy and nothing ever happened before, and I periodically walked over to my sink and touched the faucet.
If it means anything, there is this green light on my Motherboard over one of the PCI slots in my computer, it's always on.
Also, I've tried pulling the cables out of the back of my DVD drive, same thing still happened.