A while ago I got myself an used business desktop to turn into a NAS. Put a couple memory sticks in it, a small SSD to run TrueNAS, filled it to the gills with HDD. Filled to the gills, in this case, means using all 3 of its drive bays and onboard SATA connectors with two 3.5” HGST 4TB drives and one 2.5” Seagate 4TB drive. The drives were all used, the HGST bought on a used server parts website (they now have 9 years of power on time), the Seagate through eBay (and reporting almost no usage time, which of course was false). This is all too high-stakes gambling for this group, so I spared you this story.