You mean the GPU, right?
If i really push it for a huge lapse of time without cooling and my supplier says 80°C Isn't rare so heating Isn't the issue I take it.
I personally am not in favor of modifying graphics cards. The makers generally do a pretty good job of providing adequate cooling. If you feel you need more cooling, I suggest looking at your case. It is the cases job to extract heat from the interior by providing good front-to-back flow of cool air through the case. If your flow is inadequate, heat may still be building up inside the case. And a fan blowing hot air is just blowing hot air.
Besides ensuring the interior is clean of heat trapping dust, you might inspect your case to see if it will support more, or larger fans. Check for spare PSU connections too.