Question HDD not showing

[Slatey]

This has been discussed elsewhere in this forum, but I have some slightly different symptoms that I could not find there.
Got this spare PC going again a little while back, and whilst still trying to get my main PC up and running again, thought I would fit an SSD to this one. All sorts of problems with cloning, so ended up doing a clean install twice!
So I now have W10 on this SSD, and another on my HDD back-up drive. BIOS/W10 would not boot from the SSD [just a black scree], till I disconnected the HDD. BIOS did a disk scan and fixed a problem with the SSD, Now both drives boot fine when both connected and BIOS boot options are switched.
Problem - when running W10 off the SSD, the HDD does not show up in My PC, Device Manager, or Disk Management, so I can't save anything there. However, when running W10 from the HDD, the SSD does show up everywhere one would expect [so no cable issues], and I have full access to it. Only 4 SATA ports on this MOBO, and I have tried all combinations to no avail.

MB - Gigabyte Micro ATX GA-H81M-DS2
CPU - Intel I7, 3.4GHz + Intel matched fan
GPU - Gygabyte GeForce GT 710
PSU - Codegen 600w ATX
RAM - 2 x 4gb Corsair
HDD - WD Blue 1TB
SSD - Crucial CT500MX
Case - DEEPCOOL ATX
OS - Windows 10

 

[lvt]

Do you see both SSD and HDD from the Bios?

 

[General_Cool]

If your answer is a yes to what Ivt posted above, have you initialized the drive in diskpart?

 

[Slatey]

Yes, and both drives were cleaned and partitioned in diskpart before W10 was loaded on each, though first time round Windows partitioned the SSD in MBR so I had to change that [HDD is in GPT]. Then it set the partitions in the wrong order, but everything still works. Both drives are "C" or "D" depending which I am booting from. I want to prevent myself having to save all data [stuff from my other failed PC], on the HDD to an external drive, and also to not have to re-install W10 and my other program files, so initializing is a last resort. Have done clones and installs and the other stuff 5 or 6 times in the last week.

 

[Slatey]

Also wondering how to initialize a HDD I can't see from the SSD? As above, I could obviously see both drives from each other to initialize both. If I boot from that HDD and then want to initialize it, I doubt the OS would be willing to commit suicide. Does this need to be done in BIOS?
My understanding is that a clean install will erase all data from the drive, but is this the same as a clean in diskpart?

 

[USAFRet]

Also wondering how to initialize a HDD I can't see from the SSD? As above, I could obviously see both drives from each other to initialize both. If I boot from that HDD and then want to initialize it, I doubt the OS would be willing to commit suicide. Does this need to be done in BIOS?
My understanding is that a clean install will erase all data from the drive, but is this the same as a clean in diskpart?

Please show us a screencap of your current Disk Management window.

 

[Slatey]

Sorry for the delay in getting back. Was getting extremely frustrated so decided to leave things for a while before I punched the pc out. Decided to try different SATA port combinations again, after the fifth or sixth attempt with no visibility of the HDD yet, the pc crashed [no data to lose yet], and had to re-install W10. Only the SSD connected, cleaned it, but Windows couldn't find it, probably because the clean had partitioned it MBR again. Fixed that in diskpart, loaded Windows again without any SATA port changes, HDD now visible in all the expected places. Initialised that, partioning was thankfully still GPT.
OS is currently working OK, but I won't put another one on the HDD yet, just save stuff there and do re-installs if I have to.
Can't understand why Windows would randomly partition the SSD differently. Do I have a bug in my system/BIOS that is not removed by cleaning/formatting/initialising?