Hey there,
wondering if the 8GB is slower or should I go with the 11GB for a 6x card rig?
1080 Ti = 11Gb
1080 = 8Gb (with the exception of fi the MSI 1080 Gaming X Plus which has 11Gb)
I don't think the memory size difference is very important.
ATM I'm doing Nist5. My MSI 1080 8GB and my MSI 1080 11Gb are doing 66.X MH/s, my 1080 Ti is doing 87 MH/s.