Connect both the HDD and the SSD and open the BIOS menu. Are both drives listed there? If not, there may be a connectivity issue caused by the motherboard. Have you tested all SATA ports? Reset BIOS to default settings and try again. You may need to open the motherboard manufacturer’s web page and search for a BIOS update. Any chance to connect the HDD as an external drive? Check if it will be recognized.
Are you using a dedicated video card? If so, try booting while using only the integrated video and connect both drives.
Hope this helps