No I aint looking for most powerful cards, instead most efficient.
what did you set the tdp for?
a blower style card should be fully open to air if you set tdp for 85% or higher.
and fans should be at 85%.
My blower cards are set at 165 watts or about 66% tdp if they are in a case.
I also have strong fans in the case.
these are fairly strong
https://www.newegg.com/Product/Product.aspx?Item=N82E16835132027
these are stronger
https://www.newegg.com/Product/Product.aspx?Item=9SIA9ZH3S91539
I use this case for 2 card blower builds
https://www.newegg.com/Product/Product.aspx?Item=N82E16811147232
I put in 4 fans
one on top
two in front
one in back
a pair of cards set for about 65-70% tdp with 75-85% fans mining zec work well
good luck
This case can do 2 1080 ti founders at 165 watts
and 1 msi 1070 itx at 100 watts
no overheating.
please link you card as you say it is a 1080 not a 1080 ti some of them have a shitty design and don't cool well