Nikktech tried the Western Digital RED WD40EFRX 4TB SATA III HDD
A quote from the article:
Low electrical consumption, temperatures and noise levels along with excellent compatibility are just some of the reasons the RED 4TB HDD (WD40EFRX) by WD comes highly recommended for use with NAS servers.Western Digital RED WD40EFRX 4TB SATA III HDD Review @ NikKTech