Your GPU is running at 80c.. and still operational? Cripes. I thought they panicked and did a thermal cutout long before that point. Or alternately crapped out and died.
I had a laptop die once. Was a geforce 8800. There was a sliiiight problem with that line of cards.. they used a cheap solder and didn';t bake it right, so after high temp and use they tended to fall apart and fry themselves. NVidia came out soon after with the 9800 which was identical in every way, except that it didn't suffer the same problem with solder giving. Did cost a new video card (thankfully my laptop had it slotted instead of integrated so it could be swapped).
You did get really lucky, hopefully your hack holds long enough to get a new one.. and if you do keep it out of the box, so to speak, it does grant far better cooling abilities to help combat any heat-related issues.