Yes, you should be able to do something of the sort. If you hook the TV directly to the Receiver with the optical cable and then select the source for optical audio on your Receiver then whatever audio is being passed through the TV will be directed to the Receiver. I have used this type of setup in the past where I ran most of the inputs into the TV rather than using the receiver as a pass through.
In summary:
- Plug the optical into the Receiver and TV
- Plug the HDMI into the TV and Video Card (there may be a driver/control panel setting needed to turn audio on over HDMI for the Video Card, you may also need to verify that your card supports this, but most do.)
- Select the proper source on the Receiver for optical
- Now, whatever source is on the TV (in this case your PC) will be transmitted to the Receiver
Hopefully that helps! Sorry I noticed this so late.