how many volts are risers using?
What about the "issue" I've read on here that the motherboard and risers should have the same power source?
PCIe powered risers with a 6-pin PCIe power connector are 12V.
PCIe powered risers with a Molex power connector are 12V.
PCIe powered risers with a SATA power connector are 5V.
Wrong. The risers require 12V (USB risers actually require 12V & 3.3V, and have a 3.3V regulator on board). SATA power connectors have 12V, 5V, & 3.3V (some don't follow the spec and drop the 3.3V).