Well I just discovered that my ancient Radeon R9 290x uses between 275 and 315 Watts on full load.
Kinda puts things in to perspective. This card is 8 years old, I guess efficiency has improved over the years and now
with more powerful cards power consumption is naturally increasing again.
Tends to vary on each generation. The main thing the companies aim for what they thing is a good gaming performance and they tend to crank up the power accordingly. The current crop of cards use a lot of power to achieve a good hike in performance over the last generation. But there is trouble ahead, lol. It used to be the smaller the individual components on the chip, the less power they use, but this is reaching a limit now. Chips are so compact now that the very nature of the universe is getting in the way and they are getting hotter and hotter. It does make you wonder what the future is, if each generation is going to waste more power than the last.