Wow, it's super efficient with only 55w from the wall, I need to say I never see a 1660 with only 55w.
I had a few 1660 and super, but mine were using at least 70w from the wall
If you can, please share with us the wattage on miner or in a multimeter
My RTX is 3070 Ti and the cards I replaced with are ordinary gtx 1660, no Ti or super, they take less watt from the wall like 50-60 and yes few ones with Samsung memory takes up to 70watts from the wall.
I suspected of a 3070ti by the numbers
I know you have 1660 non super, I just wrote 1660s on the plural, with s meaning plural hehehe
As I said above, all my 1660 were Samsung memory, maybe with another brand of memory or new batches they consume less power
So your power consumption is even better than I thought, you made a good deal.