update - i just found out that the items linked below allow me to get another power source from the 2nd optical bay:
(though i dont know how they would interface with the PCI cards.... and I dont know if I'd need to do any soldering, or if they are plug and play..... to be determined)
https://www.newegg.com/Product/Produ...82E16812200912
or
https://www.amazon.com/6In-Sata-Powe.../dp/B007ZBYKE4