I don't know about the specs on the 8600 and would go to the Nvidia site to seek advice on this. But my GTX 470 is specced to run at 100 C and I suspect that your temps are OK. However, that said, I always think that extra cooling improves performance and electronic longevity. There are a number of aftermarket products for GPU cooling. I use and love the Zalman aftermarket cooler on my GTX 470. From the reference cooler I have reduced my idle and load temps by about 35 C.