What motherboard and BIOS version are you using? What version of Windows 10? 32 or 64 bit (presumably 64 if it can "see" 8)? What CPU?
Have you checked that you have the latest BIOS update for your PC? Does the motherboard manufacturer website have any details on Windows 10 support for your motherboard? What memory does the POST report - 8 or 16GB?
Have you tested the RAM with Memtest or similar, or removed one stick at a time to check it's working?
Is this a new install of Windows 10 or an upgrade from earlier Windows OS?
SD