Also posted this above to a previous poster but you won’t be notified so I will post it here as well.
Unfortunately it doesn’t say in the manual. It only says that if you use 4 HDDs you should use a 90W DC 19V power brick. I already ordered one, my confusion was if the 4 pin cable supports 2 HDDs but I guess since the board has 2 SATA slots and cable also has 2 SATA power connectors. I plan to most likely use 2x WD Red Plus 8TB, they use 6.2W (load), 4.1W (idle)