Thought I'd jump in the mix and give data of what I'm seeing.  I bought a Gigabyte 1080ti watercooled, and MSI Gaming 1080ti X, and an EVGA 1080ti.  The Gigabyte has the best hash rate and lowest temp (duh), the EVGA isn't far behind, and the MSI is in last place.  I'll post some numbers up soon.