Hello,   These forums are monitored by Dell employees, so I'm sure what I'm about to say is not dissimilar from what you've already heard. Our recommendation is to use validated part numbers. That having been said, many people don't and never run into an issue (I'm one of them). I can't recommend these drives, but speaking 100% anecdotally, I want to say that I've worked with a user that did have these working in their environment. 
Hello,  I recently purchased a Dell Poweredge T40  server. As per the specification sheet for T40, the recommended disks are 2 TB 7200 rpm or 4 TB 5400 rpm.  Would I be able to use an 2 X 8 TB 7200 rpm Seagate Ironwolf disk mirrored ? I am planning to use TrueNAS core for storing files.  or,  Would I be able to use 2 X 4 TB 5900 RPM Seagate Ironwolf disks mirrored with TrueNAS? Checked with Dell Support, just that they said similar to what I found on posts here. The disks mentioned in the specification sheet are validated. Any other disk may or may not work.  Has anyone tried any other disk other than the ones mentioned in the specification sheet ? Any comment/response is appreciated.    Thanks.   
Can I use Seagate 4 TB 5900 RPM NAS HDD in Poweredge T40 server?