There’s something seriously wrong with your setup since those modern SATA host controllers are known to be around ~2W with all ports connected.
Have you checked ALPM (Aggressive Link Power Management) and ASPM (Active-state power management) settings?
As for powering with one of the usual 2.1/2.5/5.5 mm barrel plug power bricks something like this may be a better choice for people not able/willing to DIY electronics:
