380 will be 20-21 MH/S , 390 with slight overclock can get you 30 so that means 50% more hashpower for 50% more money,380 will have lower power consumtion but the less haspower you have the longer time to get your money back eventually ,either way to start mining now is stupid decision....
there is still profit to be made, if you have free energy, why not? i would start now on ethereum mining, very profitable at the moment and you can always sell your gpu without problem i think
U can think that and jump the wagon but the higher the diff goes the lower the reward,price must rise also to be competitite,if it doesn't at the same rate u are fucked,new generation of video cards incoming with 14nm,much lower power consumption etc ....The only way to be sure of profitability is to:
1. Have basically free power
2. New gen of video cards to have bad hashrates and not quite great for mining
3. Enough idiots on the market to keep investing in older gen video cards so that you can sell your cards to an idiot bigger than you
4. POW will end in an year os something,you won't get your money back soon and possible never lol....
Overall,who mined from december-january and sold when time was right,or who invested and buyed when lower price and sold when time was right,or speculants who trade even for 0.20$ margin daily,these people make money from it.
you only need the first point, other does not matter, gpu have a very high resale value even after one year, so i don't know what you are talking about with the other points
970 for example can be sold easily even after the new card, for those that don't need the last gen to keep playing video game
nvidia 970 can still play any game out there, those aren't idiots, those are gamers...
again if point 1 is true, point 4 does not matter anymore, you can mine something else, and take profit, hell you can mine every shit coin out there with free energy and have your profit...