Ouch, bye bye warranty >.<

Instead of hacking the heatpipe NB cooler up, I suggest finding a new way to cool your PWMs.

It's not that hard to do, some slot heatsinks, maybe dremel it to the appropriate size, a drill, a thread taper (if you dont have it, you can even drill holes into the heatsink and ziptie it to the mobo, that works too)