GPU-Z ~ a free utility designed to give you all information about your video card and GPU. It provides displays adapter, GPU and display information. It also provides displays overclock, default clocks and 3D clocks. I use it to trace my ATI HD 4870 GPU temp and fan speed. It has log to file function. Therefore, you can trace these during game play.
ATI HD 4870 is known to have a loud fan noise. Luckily, I have SAPPHIRE HD 4870 512MB GDDR5 PCI-E silent efficiency edition which has special heat sink and fan. It has lower GPU temp and fan noise compare to reference model.
GPU-Z is a nice tool that provides all the information that you need on your display card. A great tool for overclocker like me.