No, it's not a nice choice at all. The R9 Nano is a piece of shit, stay far away from it. Don't buy into AMD's lies about low power consumption.
You said you had a HD7990 and it had insane power usage and temperature issues -- well the R9 Nano and Fury X are essentially just 2x 7970s packed onto one chip (in other words, a 7990 in a smaller form factor.) It will still draw the same insane amount of power and generate the same amount of heat, except the firmware throttles the hell out of it to keep power and heat down, meaning it runs very very slowly.
I've written a lot about this on the forums, search harder
(Hint, search for 390X or Fury instead of Nano. We were referring to the Fury X as the 390X before AMD introduced the "new" GPU as the Fury X, and just rebranded the 290X as the 390X. And the Nano and the Fury X are the same GPU.)
If you're looking for high speeds and low power consumption, consider the GTX 970 or GTX 980 instead. Although compared to AMD GPUs, even the 980Ti and Titan X have low power consumption. These are currently the best four GPUs to use with oclHashcat, there's absolutely no reason to buy an AMD GPU anymore.
You said you had a HD7990 and it had insane power usage and temperature issues -- well the R9 Nano and Fury X are essentially just 2x 7970s packed onto one chip (in other words, a 7990 in a smaller form factor.) It will still draw the same insane amount of power and generate the same amount of heat, except the firmware throttles the hell out of it to keep power and heat down, meaning it runs very very slowly.
I've written a lot about this on the forums, search harder
(Hint, search for 390X or Fury instead of Nano. We were referring to the Fury X as the 390X before AMD introduced the "new" GPU as the Fury X, and just rebranded the 290X as the 390X. And the Nano and the Fury X are the same GPU.)If you're looking for high speeds and low power consumption, consider the GTX 970 or GTX 980 instead. Although compared to AMD GPUs, even the 980Ti and Titan X have low power consumption. These are currently the best four GPUs to use with oclHashcat, there's absolutely no reason to buy an AMD GPU anymore.