Man of Honour
I just can't see how tightening the cooler can cause this. Are you sure it wasn't damaged before you fitted it and maybe missed it? I just watched a video on that cooler and when mounting it the guy said to screw it in bit by bit going from one corner to the diagonal opposite corner until the screws hit the stops. You can't overtighten it because the bracket sits on top of the pillars. If the cooler did that to the cpu I would expect socket damage as well. I have had a waterblock on my cpu's over the past 10 years or so and have always cranked the mounting screws/bolts up really tight, probably a lot tighter than any normal cpu cooler mounts manage and have never seen this before.