Okay, I was in an Apple Retail store which shall remain nameless. I was asking about an upgrade from the OEM 5770 to the OEM 5870 and was ready to plunk down my money. The "Genius" that talked to told me that it would be a better buy to purchase another OEM 5770 because my 2010 Mac Pro would be able to use the processing power of that second card even though nothing is plugged into it. WHAT????? Is he thinking about Crossfire capability on a PC? Please tell me that this is a myth and this guy doesn't know what he's talking about. Or is this somehow true? CONFUSED!