Last night following a reboot, the Samsung 960 EVO 256GB NVMe SSD was no longer detected and not even seen from the UEFI BIOS. Popping in another NVMe SSD to the same motherboard M.2 port, that other drive (950 PRO) was working fine straight away. When putting this 960 EVO SSD into another motherboard, it wasn't detected there either. Tried again on the original system along with resetting the BIOS and still no luck.
It looks like the Samsung 960 EVO had a very short life but had been running great for the past week until its untimely death, unfortunately, losing out on some end-of-the-year GPU/driver benchmark comparisons I had been working on this weekend.
Now time to see how well Samsung's RMA process works... Besides being my first NVMe SSD to die, I believe this is the first time I've ever had a Samsung solid-state drive fail on me and I have over a dozen of them running in our Linux benchmarking systems. Hopefully this 960 EVO failure was just a freak and isolated incident. Will update if hearing anything more from Samsung and how well the replacement is running.