I mean the first has better pwr characteristics and according to RS 290 is also far from "hot".
The card's temperature is not only a function of the power usage of the ASIC, but also of the cooler's ability to dissipate heat. After-market GTX480 ran rather cool and I always made a note of that to people who insisted that GTX480 ran at 91-93C as if all of them were such failures.
The same can be said of after-market R9 290s. There is no need to make generalizations as if all R9 290s run hot.
After-market R9 290/X can run as low as 68*C and as high as 85*C, but all far below the 94-95*C of reference cards.
http://www.tomshardware.com/reviews/r9-290x-lightning-performance-review,3782-7.html
With the large price disparity between after-market R9 290 and GTX970/980, it may be more cost effective to buy the 290s as a stop-gap setup and wait until prices on newer gen drop or at least see what GM200/390X brings. Buying 980 at $550+ is simply going to be a history repeating itself (GTX780Ti $699 --> $350-360 12 months later, GTX780 $650 --> $270 1.5 years later). If you got $$$ to burn, sure why not buy the best all the time. However, if there is a smarter way to upgrade, getting 80-85% of the performance while putting $ aside for the next upgrade, why not discuss that option? If you feel PhysX, DSR, CUDA eco-system are worth the $150-200 premium, sure get NV. For pure gaming bang for the buck 970 and 980 need price drops for brand agnostic GPU buyers.
I know I would pick R9 290s + i7 over 970 SLI + i5 any day because those GPUs will be upgraded in 2-2.5 years anyway, so why overspend $150-200 now for 3-5% more performance to save what $35 in electricity over 2 years? ^_^
DX12 isn't a selling point since it requires Windows 10 and DX12 games. Those won't be out until late next year which means there will be a card for $550 that will beat the 980 anyway. Right now NV can price 980 at $550 because it's competing against the 1 year old Hawaii architecture. Once AMD releases their true response to the 980, I can't imagine NV being able to sell 980 at $550. Just like most of us recommended to wait until GTX680 dropped for prices to settle on 7970s, it's the same advice for 980 since it has no direct competition right now which allows NV to inflate prices as high as
$630 for Windforce 980 - an absurd amount for a mid-range Maxwell when 780Ti is
$370.