Looks like the EVGA XC3 is the safest 3080. These are the sizes EVGA confirmed. I am going to have to play with undervolting and I have the Corsair SF750 80 PLUS Platinum for the PSU to play it safe.
Thickness of the 3090/3080 XC3 models with backplate (XC3 Ultra/XC3) is 1.78in. - 45.1mm...