Extra 25W for higher clocks on average, seems reasonable.
By a lot you mean 14-15W
For a tiny OC yes, that was @ 2062 Mhz / 2128 MHz Memory vs 1987 MHz / 2027 MHz Memory
3-4% core OC, 5% memory for extra 15w
Still like to see actual gaming power usage #s as those seem to be higher than 3dmark.
The benchmarks however were @ 2101 / 2420 or 5.7% core OC, 20% memory
So those will use quite a lot more than 15w extra, which is why its dishonest to use results from multiple different reviews just so you can cherry pick the results.
But we went from a 150 TDP (actual 160 from your post) to almost 200? That's a 30% increase in power usage. More when factoring in the higher OC from techpowerup review. Guess the 6+8 pin helps there.
Considering that card is $450 it makes it a great deal over the 1080 but very odd to compare to reference 480s.