A report has surfaced indicating that Apple may well be underclocking the ATI Radeon Mobility X1600 in the MacBook Pro. As for the actual numbers, tests showed that the GPU's core is running some 35 percent slower than what ATI suggests. The speed of the memory has been slowed, too, running 41 percent slower. More than likely, Apple is doing this to keep the temperature of the MacBook Pro down so that it doesn't melt in your lap while you're sitting at a café. ATI's own utilities were used to come to this underclocking allegation. Of course, this was all done under Windows XP, where one test showed that Half-Life 2's framerate jumped from 61 frames per second to 97 frames per second. Whether or not good ol' Mac OS X users can bump the speed up and use it to their advantage is anyone's guess.
La Radeon X1600 du MacBook Pro largement sous-cadencée [MacBidouille (in French)] via The Register