anything under 60c is fine under load.
I have an Intel Core 2 Quad Q6700 @ 2.6 Ghz. My CPU cooler is a ZEROtherm Butterfly BTF90. The case has 2-120mm fans front and back and three air vents (two on the side one in the front). My average temp. for all four cores is around 28c-31c. It can even get as low as 24c.
-I was wondering if any knew what a good temperature for a Quad Core CPU would be?