[to3m]

I've got my i7 Macbook Pro coincidentally plugged into a watt meter, and the power consumption went from 8W to 40W. (This is with the lid closed, fully charged, and an external monitor - idle consumption is more like 15W when the internal screen is active. Maybe subtract a bit if it isn't driving a second monitor. Add more if charging the battery.)

I wouldn't have thought 80°C is anything to worry about from the computer's point of view, but if using it on your actual lap I'd advise a degree of caution.