I have a Dell Inspiron 5680 with the 1tb hard drive with the Intel Optane in the m.2 slot under the gpu. I got a 1tb SanDisk m.2 SSD and took out the Intel one. When I booted the computer with the SanDisk SSD installed, it showed a boot failure and took me to the BIOS. From there, I exited the Bios and it showed me another boot failure. It was a loop and I couldn't get into the computer. Any help? If you removed the Optane before breaking the Optane cache with the HDD, the PC is not going to boot from the HDD again. You can try reinstalling the Optane, breaking the cache, and then see if PC will boot from the HDD, but I tend to doubt it. So it looks like you'll have to remove the Optane, disconnect the HDD from the motherboard, change BIOS to AHCI, and then do a clean install of Win 10 from USB onto your new SSD, and then install all your apps again. Once the PC boots from the SSD, you can re-connect the HDD to the motherboard and use the F12 boot menu to get PC to boot from the SSD. If you don't use the F12 menu, PC will try/fail to boot from the HDD. Once it boots from the SSD via F12, with HDD connected, copy all your personal files onto the SSD. Then use Disk Management to initialize the HDD (ALL FILES DELETED!) so you can use that drive for extra storage, and be able to boot directly from the SSD without the F12 menu. And last, reconfigure Win 10 to store its default folders on the HDD. Sure hope your personal files are backed up on external media... 
I have a Dell Inspiron 5680 with the 1tb hard drive with the Intel Optane in the m.2 slot under the gpu. I got a 1tb SanDisk m.2 SSD and took out the Intel one. When I booted the computer with the SanDisk SSD installed, it showed a boot failure and took me to the BIOS. From there, I exited the Bios and it showed me another boot failure. It was a loop and I couldn't get into the computer. Any help?
Inspiron 5680 wont boot after adding SSD.