There are differences in the individual chips, some will naturally run hotter than others...in addition, mounting the waterblocks is not going to be identical on all chips....so there are a lot of variables that could affect temps...as long as they are in a safe range you should not have anything to worry about.

@jjiimm_64...well, due to the outlet being limited to 20A...wouldn't it "go" before the wires (unless there is a short circuit in the wiring or something...), which should handle 20A just fine.