Re: Help! Issue with risers not fitting my larger PCI slots/Dual PSU question
actually both ways of connecting two PSUs are correct if you are using "USB" risers
As it says in the description of the Thermaltake ATX splitter cable, who also makes PSU's.
https://www.amazon.com/Thermaltake-24-Pin-Mining-Adapter-AC-005-CNONAN-P1/dp/B00O0M6Q0C
Quote
Combine your power needs with the Thermaltake Dual 24pin Adapter Cable. Ideal for crypto currency system builds and extreme gaming, optimize your power with simultaneous on/off functionality to extend your GPU performance. With independent power supplies, take your system further for more mining and ability to meet the needs of multi-GPU power requirements. PLEASE DO NOT MIX POWER CONNECTIONS TO MOTHERBOARD.
You should never mix power supplies to devices connected to the motherboard. USB risers are not electrically isolated from the motherboard and therefore it's important that all the risers are powered by the same PSU that powers the motherboard.
I also noticed BBT in some of his his latest live streams emphatically recommends that for a dual PSU rig, you need to power the risers with the same PSU that powers the motherboard and only use the second PSU to power the GPU's.
https://www.youtube.com/watch?v=lXZondkAWVc&feature=youtu.be&t=1253
https://youtu.be/pQ-EAunoAqY?t=988