Stupid question about video card...

I have a 4x agp port in my system and a 2x/4x compatible video card.  How can I tell if my video card is running at 2x or 4x?  Is it forced to run at 4x since that's what the slot is or can it still run at 2x?  I want to make sure I'm getting the most from my card.  Thanks for the help.