cpu - If I use a discreet GPU with Sandy Bridge, would Sandy Bridge's on-die GPU be sitting idle and be completely wasted?

If I use a discreet GPU with Sandy Bridge, would Sandy Bridge's on-die GPU be sitting idle and be completely wasted?

Or would the on-die GPU somehow work with the discreet GPU and still be productive?

Answer

be sitting idle and be completely wasted?

It will not be in use. Just like most IGPs on current gen Core processors.