I've got 2x 14tb WD EasyStore drives, 7200rpm drives inside. Under 17k hours on both, SMART available if interested. $165 shipped ea (+fee if G&S). Let me know if interested.
I have a Gigabyte B450M board listed here: https://hardforum.com/threads/fs-gigabyte-b450m-ds3h-evga-1600w-p-psu.2038647/
Have a few PSUs to pick from: Apevia 800w 80+Gold, Corsair CX430M (might be tight for a 3950x), Seasonic Focus 650w 80+Gold.
Have some coolers, too - Cooler Master 120mm AIO...