I have the opposite problem of you, my gtx260 fails to pass 65C on 40% fan(palit gtx260 sonic)
If you dust things out, it will do wonders, if the warranty is out, go buy coffee filters and some thermal paste eg: ocz freeze,acrtic cooling mx2, tuniq tx-3. Stay away from ac5, it takes long to cure and if you put too much, it can lead to problems near your graphics card chip.