:facepalm: Overclocking is fun and useful. You can't kill a card that new with it unless you edit its BIOS restricting the extreme core voltage modifications. Hell, even the warranty covers overclocking since it's not logged anywhere.
It consumes a lot of power, but it's also a very high end model. Actually, it was a top model only a couple of years ago and seeing that no "benchmark" games have been released since it will still run anything maxed on a single monitor.
If it works now, there's no reason it would suddenly die after changing the owner.
If your knowledge of computer components is none or horribly outdated please do not mislead people asking for help.