What model 8800Gt do you have? You said it has 65-70C idle temps. What are the load temps? Also, what are your ambient temps? (ie. the room your PC is in).
Some 8800GT models have smaller coolers and run hotter. I have a spare 8800gts in my computer right now and it has a dual slot cooler and idles at 60C. an 8800GT has a single slot cooler and would idle much higher so this doesn't seem off to me. Load temps would tell us alot.