Here is my experience with heat issues, I was running two 8800 GTS G92 512mb in SLI in my last system and had heat issues which did not make seem right cause I had plenty of fans for the case, top included. It was not too bad so I did not think much of it (temps where high but not critical).
Then as I was upgrading (seems I never stop..
) I noticed a nice drop in temps after putting in a stonger power supply. I looked at some general specs for you video card and found that it recommends a 500 watt min, your current power supply should be more than enough but again just my experience as my old system "should have been more than enough" also.
Once I had the new power supply my temps on video dropped around 10C! Could just be that I went to a better quality, or maybe that my new PS has a single 12v rail, or who knows. Also through the trickle down my dads PC got my old PS, better than he had, and I saw CPU and video temps drop.
Don't know if you are wanting to go out and replace your power supply but hope the info can give you another option.