I recently purchased an SSD, ADATA SP920 128GB, installed Windows 10 Pro onto it, and all was fine. However, when my old HDD is plugged in at the same time (as I wish to keep using it for storage), Windows freezes after a few minutes, although I can still move the mouse, just not interact with anything. The SSD is in the first SATA port on my motherboard (specs below). For some reason only one SATA drive appears at any time on my boot menu, which is at first the SSD although the HDD is still visible in the system information tab. After the freeze, the SSD is no longer seen on the boot menu, or in the system information tab, as if it wasn't there at all. This problem does not occur at all when the second drive is not present. The cables are not faulty (I swapped them to no avail). I feel this may be a BIOS / motherboard issue as opposed to a drive one. Any help would be extremely appreciated, thank you.
Specs
MSI Z77A-G41
I5 3470
2 x 4gb DDR3 RAM
Seagate 7200 1 TB
ADATA SP920 128gb
Palit NVIDIA 1060 6gb
EDIT:
So I reformatted the HDD, and reinstalled Windows onto the SSD. The problem persists; if both drives are plugged in and I boot from the SSD (the only available boot drive now) Windows freezes after a few minutes. When I restart, the SSD is no longer recognised by the BIOS so gives an error stating that there are no boot drives available. After a second restart, the problem repeats itself. However, if I only use the SSD, which is only a temporary measure, it works completely as normal. Not a clue why this happens at all, as the cables are fine, as are both drives. Cheers for the help.