Create VST-sounds at 192khz/24bit when soundcard only supports 48khz/16bit?

hey!
 
i started a draft yesterday about soundcards and got some helpful reply, but one question still remains and because it is quite a topic of its own i thought it's better to start a new thread)
 
So my question is this:
I want to edit and process audio tracks (wav files that i drag into Sonar from my C: drive etc) at 192khz/24bit (i know this is debatable, but that's not my question...) and i also want to create sounds with vst-synths at 192khz/24bit.
Therefore i set the preferences in Sonar to 192khz/24bit.
 
Now: is it NECESSERY that my soundcard can support such high values to even work inside SONAR at these rates (create sounds with VSTs and process audio files) or is it possible even with an internal soundcard that can only support e.g. 48khz/16bit ?... Cause I know already that it's not necessery for rendering and exporting from Sonar at 192khz/24bit.