Ok, this is not as simple as it initially sounds. I have a hard drive that is not detected in Windows (8.1). The activity light just stays on. It will however work in another computer just fine and I ran an extended SMART test and there are no issues. I've tried different ports and cables on the motherboard it does not work with and still nothing. The model of the drive is HD753LJ and the mobo is ASRock z87 Extreme11 a/c. It's a fairly old drive and a pretty new motherboard. I thought maybe they just had compatibility issues or something. The odd thing is, I have another hard drive of the exact same model and it works fine, even in the same port and using the same cables as the one that won't work. I've do IT for a living and I gotta say, this one has me stumped. Any ideas? Firmware issue maybe? That's about all I can think.