The R9 290(X) were build to run at 95c. The fans wont sweat until you reach the 95c if you didn't set the max temp lower.
I'm running my 290x with an AIO. Stays at 61c full load.
Wonder what you are planning to mine with the 290.
R9 290 thermal limits at 94, on the reference-board design.
NOT a good idea to let them get that hot though, they're a lot happier for the long term if you can keep them down to around 80.
290 is still a good ETH mining card, though I'm not sure that's the BEST option.
I have some R9 290. But I only run them at 900mV or lower. The temperature is below 70 degree C. They are long lasting.