After I noticed the HDDs getting really hot in the SilverStone DS380B, I 3D-designed and 3D-printed a cooling duct.
A small form-factor DIY NAS featuring FreeNAS, a Supermicro X10SDV-TLN4F-O motherboard, Intel Xeon D-1541 CPU, 64GB DDR4 ECC RAM, 2x 10GbE, SilverStone DS380B case, and 40TB of total storage.