While it is true that they help to cool down the chip, they are usually mounted upside down. As true gamers this is unacceptable because it means you can be severely limited in your ability to overclock your graphics card due to heat-related issues. So short of manually adding a cooling fan, you do have a viable alternative. The good ole' slot cooler. Cooling is not an area that you should ignore or overlook.
Most people sink a lot of cash into having a killer gaming rig.
It makes no sense to take a vested interest into that rig and keep it cool. In the long run you'll end up with a computer that is not only cooler, but also lasts longer and runs more stable.