Not sure about the 1060TI, I would expect that it will work though just may need additional VIDEO POWER adaptors, need to check the card. The S20 is only BIOS.
I would like to know what video card you put in as well. I recently bought the same thinkstation s20 and might want to upgrade the video card. I have an Nvidia Quadro 4000 2gb card in it right now which is plenty fine for my uses for it for now but why not upgrade for fun?
In the video you say this model can have multiple video cards, so why not keep both of them? Also, I have Firepro v3700 so can I also install Nvidia Quadro fx800 side by side?
Updating the BIOS is always a good idea. The hardware you should not but always check the power requirements of the video card. Like auxiliary power cables.