1 year back, one of my very new rigs was taking 450 Watts on the wall.
Now I've just checked and it's consuming 600 Watts for the very same hash rate.
Does the efficiency go down this much of the hardware?

What about the temperature on the cards and ambient? Has that increased?
Power consumption is side effect of increased performance. Claymore has optimised the miner significantly since 1 year ago. Thus increased power consumption.
A big yes! Temperature has been extremely high too along with the increase of power. But hash-rate hasn't changed/increased.
Temperature now with 100% fan is around 90, never happened before.