I purchased two single rail Power Supplies to power my two hubs, one is rated at 850 watts and the second at 700 watts, so I have plenty of power with at least 30% "spare". Also, I opted for high quality power supplies rather than lower cost power supplies. I've purchased lower cost power supplies for high end PCs before and have had three fail within 18 months of purchase, so I stay away from low cost ones now.