PSU was all that showed up on new egg after filter by single rail, 12 sata power connectors, modular, and main 24 pin connector. I chose the corsair since most people rate them as high quality. As far as the motherboard, I picked it because I need to support 24 drives in the 4224. Granted unraid only supports 22. 2 controllers with 8 ports + the 6 onboard would give me 22. So I wanted to have another just in case I needed the additional 2 disks and unraid began support it or for anything I might want to add later.