nvidia-smi (part of nvidia-drivers-260.19.36) does not work as documented 'nvidia-smi -q' is expected to supply useful information such as videocard temperature. But it only shows drivers version I suggest that bugreport be sent to NVIDIA I enclose output of 'emerge --info nvidia-drivers'
Created attachment 272815 [details] output of 'emerge --info nvidia drivers'
It doesn't necessarily work on all cards. The interface is only available on Quadro cards according to their documentation. If you have any questions about this utility, please contact linux-bugs@nvidia.com