I like Hardware Canuck's review. For the simple fact hey tested 8XFSAA (a setting one would expect people to use on these power house cards) as well as measurements of minimum and average FPS in a variety of games (Including Just Cause 2!).
Their temperatures are lower than other review sites, but I see this is because they did a real world test (i.e not the anomaly called Furmark which switches every transistor to on... an impossibility in the real world of gaming etc).

I may be accused of trolling or nVidia fanboyism, but there is no mistaking that the Radeon 6990 is the fastest graphics card in the world (for domestic use of course) full stop. However I am sat here, quite happily using my Single PCB GTX 295 and am wary to upgrade to the Radeon 6990 because of the noise. May sound odd, but my card is not that loud in gaming...

I await reviews of the GTX 590 before I will come to a decision.

If the GTX 590 is within 10% of the 6990, but a lot cooler and a lot quieter then I will elect to go the nVidia route.

To me the noise and heat are big negative factors which mar an otherwise fantastic and wonderful card. Perhaps Sapphire may release a Vapour-X edition?

John