Q:

Samsung 830 seen in BIOS but not Windows 8 on Dell XPS8700

So this is odd: I have a known-good Samsung 830 256GB SSD which my new Dell 8700 Special Edition sees in BIOS, however it's not visible at all in Windows 8.1.   This drive works fine in my old computer. 
In Windows, I've checked the Device Manager and the Disk Manager, and neither shows an entry for this drive.   The Samsung Drive Magician doesn't see it either.    I'm using all the BIOS defaults, so the SATA mode is 'AHCI' (rather than RAID; that's the only other option). 
Any suggestions on what else to try? 

A:

Wow, that was a hair-pulling experience. 
The answer was disabling SecureBoot in BIOS and rebooting the PC.   The drive suddenly appeared as a new, uninitialized drive. 
There was data on this drive from my old machine, but I had a backup - so I merely formatted it and assigned it a drive letter and all is well.