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Thermal Throttling Cripples Apple's Macbook Pros Using New Core i9

The thermal solution inside Apple’s newest professional laptops may not be up to the task of keeping the fastest processor running up to spec.

Chris Jarrard

July 23, 2018 10:55 AM

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When configuring a new top-of-the-line Macbook Pro on Apple’s website, you’ll have the option to include Intel’s 2.9GHz six-core Core i9 CPU for an additional $300. Before you complete that transaction, you should know that early reports from users claim that the laptop is unable to keep the Core i9 within its thermal limits, resulting in performance throttling when the laptop is under a heavy load. The issue was first brought to light by Youtuber David Lee in a video he made about the new 15-inch Macbook Pro with the Core i9. The findings from that video have also been corroborated by other tech outlets since the video was first posted.

Modern CPUs automatically adjust their speeds based on a few factors, most importantly by the power required of a computing workload and by the thermal limits of the CPU itself. The Intel CPU in question is sold as a 2.9GHz six-core solution. When presented with a heavy load (and with proper cooling), the CPU can automatically boost one (or more) of its cores up to 4.8GHz. The wide range of operating speeds allows mobile (and desktop) users to have access to cutting-edge processing power while controlling power use to prolong battery life. This is especially important for laptop users.

Due to their size, laptops are known to make tradeoffs in performance to make gains in power efficiency and temperatures. The Core i9 CPU that comes in some of the new Macbook Pros has a default clock speed of 2.9GHz while its desktop counterpart is sold as a 3.7GHz part. Most desktop PCs have the space to accommodate better cooling designs, while laptops must get by with less space and smaller fans. The design of the Macbook Pro cooling system is just over two years old now and is simply not up to the task of dealing with a big, power-hungry chip like the Core i9.

Testing from David Lee (as well as AppleInsider) show that under a heavy workload from Adobe Premiere, the Core i9 in the new Macbook Pro is operating anywhere from 2.3 - 2.65GHz, under the rated 2.9GHz speed and a far cry from the advertised TurboBoost speeds of 4.8GHz. AppleInsider found that the Macbook Pro with the Core i9 was unable to complete the rendering task any faster than a comparable Apple laptop with the slower Core i7 CPU. While keeping the Core i9 cool is a challenge for all laptop makers, tests done on other manufacturer’s units do not show the same CPU operating under the baseline spec.

As of this writing, Apple has yet to address the issue. While many are blaming the company for pairing such a hot CPU with an inadequate thermal solution, others are pointing the blame at Intel for its failure to deliver faster, more efficient CPUs on its originally promised production schedule. In the meantime, if you are in the market for a top-of-the-line Macbook Pro, you may want to consider avoiding the Core i9 option until Apple offers a software solution or a change to the Macbook Pros cooling design.

Chris Jarrard

Contributing Tech Editor

Chris Jarrard likes playing games, crankin' tunes, and looking for fights on obscure online message boards. He understands that breakfast food is the only true food. Don't @ him.