Hy guys. quick question: my card reaches 100 C degrees. is that normal?

I have a Leadtek GTX 560. with stock cooling used to go around 80-90 degrees C stock frequencies, no good since i had overclocking in my mind.
I opted for an Arctic Cooling Twin Turbo 2 as I read a lot of good reviews about this cooler.
Guess what..... now my temps go up to 100C routinely after 3-4minutes of skyrim.
Tried different configurations of fan's and varying the amount of thermal paste even created a custom backplate to help distribute the pressure, anything short of water cooling... the only way of keeping the card at decent temperatures is to cripple it with under clocking

At this point I'm thinking that perhaps I damaged the card while fooling around with it, or over-tightened the retaining screws.
Overall the heatsink seems really cool to the touch while the gpu reports those ridiculous temps so I think it could be the Heat Spreader.
What do you guys think, is removing the IHS my only option?