MacBook Pro has Underclocked GPU?


Apple has reportedly underclocked the Radeon X1600 GPU on its Intel-based MacBook Pros, Moneycontrol reports.

Apple has apparently done this to conserve battery life. The 'feature' was discovered after some users installed Windows XP on their MacBooks following Apple's release of Boot Camp.

The core clock speed is throttled down by over one third, and memory clock speed is reduced by 41%. At full speed, the GPU runs at 470MHz, but Apple sets the hardware to run at 310MHz (core) and 278MHz (memory).

The MacBook would be likely to run at up to 30 minutes less on battery if the GPU ran at its full potential. It appears to be system-controlled, so the GPU will run 'uncapped' at full speed on Windows XP.

Analysis: This isn't exactly new territory for Apple; they're overclocked G3/G4 chips in the past, and underclocked chips as well. System buses have been run at lower speeds, say, on iBooks, to increase the performance differential between iBook G4s and PowerBook G4s. The G5s, however, did not suffer from this kind of performance hobbling. Apple has also left L2 caches off chips (PowerBooks 5300, 1400/117 and original Wallstreet G3/233), artificially restricted readable memory (LC, LCII), and hobbled DVD Superdrives (originally no support for -/+RW or DVD+R).

But it's a little embarrassing that you need XP to make your graphics chip run faster.