Was just updating the carts for my hardware today when I saw this little (big) 14 page review.
BenchMark Reviews 80-way Thermal Compound Test
I was surprised to find that the Compound I use, OCZ Freeze, with an A. But not surprised to find the highly renowned Arctic Cooling MX-2 high up there with an A-.
Mind you, I choose OCZ Freeze because of its viscosity
and the way it performs on my TT 775D.
I really suggest you read the whole article rather than clicking next 13 times to read the grand results. There's a lot to gain from their time and hard work.