Your idle temps seem a bit high , they should normally be around 48-50 c. My 8600gt (720/800) idles around 49c and goes till 74c on load. Try installing a fan blowing air onto the card.
how is it possible tht ur load temp is just 11C higher than idle? :S :S
anyway, if ur load is around the 70C mark then the temps are fine.
if u want better cooling u cud try doing a fan-mod using 120mm fan directly over the heatsink. or u cud always go for aftermarket coolers