This is from a review of the Radeon 9800 Pro:
"When tested outside the PC case, the sink reached 70-75 degrees C after a 10-hour operation in 3D! Imagine how hot the insides would be! That is why if your PC case doesn't have good ventilation, you can easily damage the card and some of the components inside the PC case!"
Another recommendation I've read says the PSU should be rated to at least 400watts for this card. TC.