I have used a 5.25" mounting bracket to replace my Acer E1-531G laptop's optical drive with a 2.5" 32 GB Transcend SSD. The main drive is a 750 GB HDD.
After setting up a partition in Windows Disk Management, the SSD shows up as drive E:, and files can be written to it. I cloned the Windows special partition at the start of the HDD (presumably a boot partition) and C: to it.
However, when I go to BIOS, the SSD does not show up anywhere, and therefore I can't boot from it. Both partition tables are MBR, all partitions are NTFS, the OS is Windows 10 Home 64-bit, BIOS is InsydeH2O v3.7, BIOS is set to boot in Legacy BIOS mode, not UEFI (Windows won't boot otherwise, and no boot devices at all show up). The BIOS does show USB FDD and USB HDD as boot options, and can attempt to boot from them even if they aren't bootable - so the BIOS should show the SSD regardless of whether the cloned partitions are valid and bootable.
Based on threads elsewhere with this or similar problems, I have tried:
- resetting the BIOS to factory settings (no effect on list of bootable devices)
- restarting the laptop many times (no effect)
- removing the HDD (no bootable device found, SSD still completely ignored by BIOS)
- switching to UEFI mode (no bootable device)
- switching the harddisk controller from AHCI to IDE and back in BIOS (no effect)
- removing the battery from the laptop and waiting a few minutes before reinserting it (no effect)
- booting Windows in recovery mode and running boot repair ("could not repair your computer").
I have not yet tried and am scared of:
- updating the BIOS
- swapping the positions of the HDD and the SSD
TL;DR: Installed new SSD, does not appear in BIOS but does appear in Windows.