I run mid 50's C for temps in most games, Star Citizen will run it up to 70c with all settings maxed.
Which is still a very safe temp for a 290x. I guess the Vapour-x runs cooler, but it is quite expensive, which is why I got a Tri-x.
However.......3xx cards will be announced soonish. I cannot reccomend anyone buying a high end card for the next month or so unless they have to, because let's see some benchmarks on the 3xx cards, and let the makers like Sapphire come up with good cooling solutions for these new cards.
Even if you still go for a 290x, it is very likely it will be cheaper, soon.
I got mine about 6 months ago. It was NOT cheaper lol.