I see 100% GPU usage (and temperatures in the 70-75 deg C range) for D:OS, but it's far from the only game showing such behaviour.
For anyone seeing higher temperatures, I'd agree that system cooling needs to be looked at. The simplest fix (for desktops) would be to take the side cover off and point a desktop fan at the GPU - if this works, then install a couple more internal fans for GPU cooling (one on the side of the case, drawing cool air directly onto the GPU should help matters).
Another possibility is too much (or too little thermal paste) on the GPU - to check this you would need to take the GPU out, remove its heatsink and re-apply thermal paste (the instructions
here are comprehensive).
Multiple graphics cards (Crossfire or SLI) can present a particular problem since the heat from the lower one may be picked up by the fans of the higher if you have a case that mounts the motherboard upside down. In that case, try moving the cards to different slots (if connectors allow) to increase the spacing between them, or add extra fans behind the cards to blow hot air out of the case more quickly.
