So if you don't understand then that makes me much smarter than you, okay, first polaris is done for right, hashrate is decreasing, amd even claymore or other people dont know if they can fix that, second Vega is a new arch which means problems like we see on polaris might not affect Vega, Vega will have gddr5 versions, will not be only hbm2 versions which mean, Vega is the only thing to make a case and compete x nvidia 1070 concerning miners, they will probably place it around gtx 1070 price, that is a reason amd will not fix polaris, because amd want miners and gamers to make their vega arc a success.

Remember, after polaris is done which will be in 3 or 4 months then to match or surpass the gtx 1070 in hashrate will only be a Vega + gddr5.

Concerning power consumption, performance/power, lower vega models with gddr5 might not use that much power.