A fairly common issue I've found with both custom built as well as pre-built OEM PC's is the display driver nvlddmkm driver will stop responding within the 1 sec TDR delay set in the Windows registry which will cause the display to either go black on else flicker and recover. But then many users will still find they have to re-boot their system... or sometimes not.

What I don't want to spend too much time discussing is all the testing I've already done and also all the troubleshooting already performed. With 100% certainty if asked, did you try this, or did you do that, the response will be undeniably 'Yes. Been there, done that'.

The only thing that hasn't been tried is underclocking the Nvidia GPU. One might ask, who the heck would consider doing that? There's been users who've posted on other forums that it has worked (for them) to correct this issue.

It was my understanding Dell GPU cards are clocked slightly lower than the reference specs. Nvidia specs for my GPU clock are 1506 MHz and the GPU boost of 1708 MHz.

Perhaps trying MSI Afterburner to lower the Core clock to a negative (-) boost range may work

Both GPU-Z Tech Power Up and HDWInfo64 sensors read the graphics clock of 1911 MHz. I wouldn't consider messing around with undervoltaging since I'm informed enough to know of the possible cause of damage to the GPU. 

 Anyone tried underclocking and if so, did it work to fix black screens, and critical error 4101 "Display driver nvlddmkm stopped responding and has successfully recovered" ?     

HWInfo64GPU-Z Tech Power-Up