Strange Intermittent SATA HHD issue:
I have a custom built PC running Win 10 with three internal HDs
MB: Gigabyte Z170XP-SLI-CF https://www.gigabyte.com/Motherboard/GA-Z170XP-SLI-rev-10/sp#sp
CPU: Intel® Core™ i5-6500 CPU @ 3.20GHz
C: Samsung SSD 850 EVO 500GB (OS and programs only)
D: Seagate ST2000DM001-1CH164 (Documents, music, everything except pics)
E: Western Digital WDC WD20EZRX-00D8PB0 (Picture files)
A week ago Carbonite notified me while I was using my PC that back up was frozen because one of my drives was missing (Drive D). I dug around various Windows places to check for any sign of the missing HD. It did not show up under device manager or most of the other control panel windows but one screen came up (unfortunately I forget how I got to it) did show all three HDs but this screen has very little specific info. No drive letters or info on HD model BUT it did correctly report the max memory of each drive, used memory and available memory for all three HDs.
Before crawling under my desk and opening the side panel I decided to try some debugging with my Advanced System Care utility. No problems were detected except when I ran a Registry Scan reporting mainly some invalid shortcuts. I ran the auto fix option, rebooted and my missing HD was back BUT my Desktop background setting turned completely black instead of my normal background image. The next day my background returned.
Worked fine for a week and then the same drive did the same exact thing with the same diagnostics and control panel results accessible from Windows. ASC again found no issues and no registry issues as well. Although there were no unusual sounds I assumed the HD was likely starting to die and picked up a replacement HD two days ago.
I didn't check the status of the disappearing drive before buying one online to pick up in the store later that day but right after placing the order I noticed Mr D drive was back in perfect action and has been ever since. Not wanting to go through the hassle of replacing the drive right now if not necessary I ran a built in Windows HD health assessment utility that reported no problems. Next I downloaded HDDScan for Window V 4.0 and ran their shorter "Smart Test" which came back clean. Then I ran a "Butterfly" test with "read data to the hosts with seeks" that took a little over 24 hours but also came back reporting everything normal but I don't think it is any kind of HD stress test.
I do have a bootable ISO Mem Test 5.01 I haven't tried yet but not sure if it is the right debugging tool for this job. I'm guessing based on the intermittent all or nothing behavior that it is more likely to be an electrical component issue or possibly a spotty SATA connection?
Good news I suppose is if my D drive does crash it is backed up and I have a new replacement ready to install. Bad news for me is I am way over my head knowing what kind of additional HD tests might be useful and which ones are a complete waste of time.
Any recommendations on additional diagnostic tests for an intermittently working HD that works perfectly normal performance wise when it is recognized by the OS or MB but occasionally fails to show up at all?