Those 1,21 Volts can be only applied with Evga Precision or Nvidia Inspector mate
Do the following steps one after another and you´ll be good to go :
1. flash the card with whatever bios you wanna use ( stock , sykn3t .... whatever )
3. uninstall every typical tool for overclocking / monitoring of your gpu ( precision & afterburner most of you guys probably have )
5. uninstall Nvidia driver with DDU
7. install prefered Nvidia Driver ( driver doesent realy matter´s at least in terms of voltage delivery )
9. for Overclocking / Volting install one of those : latest EVGA Precision X , Nvidia Inspector 18.104.22.168. <- this is what i use
10. Setup your clocks and voltages and everything should be fine
Now everything realy needs to work at least in terms of voltage delivery
You need to understand that using MSI Afterburner doesent crank the Voltages on your 780 Ti´s GPU Core up it only adds the voltage to the GPU itself but that doesent help you stabilizing your actuall Overclock .
However if you want to use Afterburner for 64 Bit Monitoring be sure to untik "Hardware Controlling and Monitoring" under Afterburners options so that there is no way Afterburner can manipulate any of your clocks or Voltages and use Nvidia Inspector for Overclocking .