If you are using a generic/retail drive or another OEM's drive, then it will always show as not being certified and will give the non-critical warning. You should be using certified drives. If using non-certified, then do all or nothing.
I recently had a predictive failed hard drive in the Raid 0 array of my Poweredge T320 running Windows Server 2008 R2 Standard.  I replaced the hard drive with a brand new match.  It was a Seagate replacement and not from Dell.  When i put the drive back into the array, it rebuilt over night with no issues.  I think the Server rebooted itself overnight due to pending updates.  I dont know if the rebuild was completed at that point or not but it is complete this morning.  The new drive shows up as State: Online, Power Status: Spun Up, and no predictive fail notices.  However, the status is still showing Non-Critical instead of OK.  The rest of the drives are all showing OK. The only difference i can tell between it and the others is that the Manufacture information is not available, it is not listed as certified, and the Vendor ID is Seagate instead of Dell. What could be causing the Non-Critical status?
Rebuilt Hard drive Not Recognized