AMD power efficient gaming PC - what AMD CPU and AMD GPU can be used?

Then why do you ask for an AMD GPU? If you will only consider power efficiency then choose NVidia.

1050 Ti is not close to an RX 470 in most games, and all previous generations of graphics cards have worse power efficiency.

Almost beating? There's a ~10-15 FPS difference in any benchmark on the internet....or more....I wont call that "almost".

idk if you know but 15-20 fps of 60-110 fps is fuking a lots
performance per watt
GeForce GTX 1050 Ti 8.4
Radeon RX 480 8.9
so rx 480 is less power hungry than the 1050ti, so i seriously don't understand your point

Bitcoin mining
Radeon RX 470
494.55 mHash/s
GeForce GTX 1050 Ti
326.38 mHash/s

Face detection
Radeon RX 470
111.59 mPixels/s
GeForce GTX 1050 Ti
94.59 mPixels/s

Ocean surface simulation
Radeon RX 470
1,862.86 frames/s
GeForce GTX 1050 Ti
1,136.83 frames/s

T-Rex (GFXBench 3.0)
Radeon RX 470
3,359.1
GeForce GTX 1050 Ti
3,352.2

Fire Strike Factor
Radeon RX 470
65.08
GeForce GTX 1050 Ti
51.6

Sky Diver Factor
Radeon RX 470
367.8
GeForce GTX 1050 Ti
335.39

Battlefield 4
Radeon RX 470
77
GeForce GTX 1050 Ti
66

Crysis 3
Radeon RX 470
48.9
GeForce GTX 1050 Ti
35.8

and now 480 vs 1050ti

Bitcoin mining
Radeon RX 480
608.32 mHash/s
GeForce GTX 1050 Ti
326.38 mHash/s

Face detection
Radeon RX 480
120.17 mPixels/s
GeForce GTX 1050 Ti
94.59 mPixels/s

T-Rex (GFXBench 3.0)
Radeon RX 480
3,356.26
GeForce GTX 1050 Ti
3,352.2

Manhattan (GFXBench 3.0)
Radeon RX 480
3,717.86
GeForce GTX 1050 Ti
3,704.39

Fire Strike Factor
Radeon RX 480
75.65
GeForce GTX 1050 Ti
51.6

Sky Diver Factor
Radeon RX 480
413.57
GeForce GTX 1050 Ti
335.39

Battlefield 4
Radeon RX 480
82
GeForce GTX 1050 Ti
66

Bioshock Infinite
Radeon RX 480
110
GeForce GTX 1050 Ti
75.9

if you can't spent 1-2 $ a years of extra electricity cost, you don't have the money to buy a new comp, might be rude but i can't see any other reason to be so low on power even if you spent extra 100+ $ for nvidia/intel