One good way to check compatibility is to search for benchmark of this model. Area 51 R2 is reported to work with RTX3080.  [URL] is in the same series as 3080. while you were able to run two 1070 before, not sure running 3070 + 1070 would need a higher power rating psu such as 1500W.
Hello, I have Area 51 R2 that's a little over three years old.  It came with a GTX 1070 and I added a second to it.  I'm wondering if the new GTX 3070 will work in it.  I would replace my addin 1070.  My  if that helps.  Thanks, Johnny
Area-51 R2, GTX 3070 compatibility?