Looks like Apple is in fact using the Mobility version of the X1600 in the new iMacs. Bummer. Compare the actual shot of the guts of the iMac (thanks, kodawarisan!): to the ATI product shot of the X1600 Mobility: Same chip (looking at the components around the chip). For comparison, here's an ATI product shot of the desktop X1600 chip: I understand why they would use a Mobility chip with the iMac's space considerations, but I think it's a bit deceptive of Apple, as they specifically say "X1600 Mobility" in their specs for the MacBook Pro, but only say "X1600" in their iMac specs, which might lead one to believe the iMac uses a full desktop X1600.