Hello, can somebody explain to me Efficiency column ?

#gminer v.2.14 @ kawpow

RTX 2070s default
22.15 MH/s,  145 W,  155 KH/W

RTX 2070s OC+PL
23.03 MH/s,  134 W,  170 KH/W

My card is using less power and runs cooler but I'm loosing efficiency? KH/W column must register low numbers?

Thanks.