Ok, that’s severe. Rather sounds like a hardware issue. You can try setting manual mode to test if the fans are working at all.
To enable manual mode, use the CoolBits option in xorg.conf:
https://download.nvidia.com/XFree86/Linux-x86_64/384.98/README/xconfigoptions.html
Then set the speed using nvidia-settings
If the fans still don’t spin, RMA the card.
https://forums.developer.nvidia.com/t/how-to-set-fanspeed-in-linux-from-terminal/72705/6