I have a rig setup with two MSI AMD 7950s. I am running at the default clock speeds... not overclocking anything. The temerature of the GPUs are around 84C. I have the case open to let the heat escape. Is it safe to keep this setup running 24x7 ? What is a safe point and when do I need to worry?

What can I do to improve the temperatures? I am planning on putting a large fan that will blow air into the GPU cards.