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My iMac thats in my sig runs the latest rev of Crysis with everything set to max except AA which is off. Very rarely do I see a frame rate drop to where it is actually noticeable to the human eye. Apple may not use factory overclocked, water cooled $1000 video cards in SLI, but there choice of cards is good enough for gaming without blowing a hole in our budget.
 
People are bundling together two or more 4870 class cards on machines with i7 Quad Core processors so that they can see Crysis in all its glory, running at 1600X1200 or greater resolution with all the details turned on and a framerate that doesn't dip below 60fps.

Compare that to gaming Crysis on the top spec iMac and being lucky to get a 50fps frame rate with a lower resolution and details set to medium and you can see why the iMac is no substitute for a gaming PC.

Bingo! We have an answer. While the iMac can play Crysis and many other games decently it will never match up well with a well built gaming pc.
 
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