I see many people recommending not using SATA to power the risers at all and that running multiple is a potential fire hazard. See: https://www.reddit.com/r/gpumining/comments/6pqb8i/question_about_safe_power_draw_for_pcie_risers/

If your running 5 risers on 2 chains that might be an issue since SATA cant provide enough power per chain. If you can run the risers directly on molex from psu i think that would be preferable.