Apple's New i9 MacBook Pro Runs so Hot It Has to Slow Down

Users are reporting that the new 15-inch MacBook Pro is throttling speeds because of heat issues.

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Jul 19 2018, 12:00pm

On paper, Apple’s new 15-inch MacBook Pro is a beast. The slim laptop comes in a variety of configurations that range in cost from $1,300 to upwards of $7,000. One of the big draws this year is the option to upgrade the 15-inch model to a an Intel i9 processor. The six-core 2.9GHz processor is a powerhouse and comes unlocked and overclockable, meaning users can push it to run even faster. But Apple fans are skeptical, especially after one YouTuber benchmarked the i9 model and discovered it throttled the CPU’s processing speed when trying to render a video in Adobe Premiere.

Now, Apple fans on Reddit, Facebook, and Discord are complaining about the i9 and the few people who’ve already got the new MacBook Pro are running benchmarks and pushing the machine to the limit. It’s a telling reaction from a community that’s lost some trust in Apple. Last year the public learned it throttled iPhone batteries in older phones to encourage people to buy new ones.

Redditor Aea discovered his MacBook pro slowed down after 5 minutes of running Prime 95—a CPU intensive number crunching program. After just one minute of Prime 95, the i9 had dipped from a 2.9 to 2.5GHz. Cinbench—another benchmarking program—showed similar dips in performance. Several other redditors on the thread chimed in to say they’d gotten similar results and planned to return the MacBook Pro to Apple.

Aearan this endurance test on both a 2014 i5 and the new i9. Both throttled, but the i9 throttled much worse. He ran two versions of both tests, one with the systems fans set to maximum and another with the system set to automatically manage the fans. When the system handled its own fans, the performance of both the i5 and i9 tanked. At one point, the i9 throttled down to 800 megahertz. “This hints to me that there’s something wrong with these fan speeds,” Aea said in a YouTube video about his tests. “Apple is prioritizing low noise, low RPM over performance.”

YouTuber David Lee—who does hardware reviews and tutorials at his channel Dave2Dexplained the problem in a video posted Tuesday. “It’s a very powerful CPU, when it comes to multi-core applications, this thing is a beast,” Lee said. “The problem is that when it comes to this chassis, the MacBook Pro can not cool the i9 properly.” Lee tested the chip by rendering scenes in Adobe Premiere—CPU intensive video editing software—and found that the new MacBook can only hold the i9’s base clock speed of 2.9GHz for a few seconds before it throttles the speed down to 2.2GHz to prevent it from overheating.

Lee compared the new MacBook pro to an Aero 15X laptop running the same application with an Intel i7 with a base clock speed of 2.2GHz. The Windows laptop had an average clock speed of 3.1GHz. “The i9 in this laptop can’t even maintain the base clock speed,” Lee said. “Forget about turbos and all that stuff. It can’t even the 2.9GHz base clock. Which is absurd.”

Lee further tested the processor by rendering a video in Adobe Premiere and comparing it to last year’s MacBook Pro i7 and the same Aero 15x. Adobe Premiere isn’t optimized for Apple products and the Windows machine blew through the render in just over seven minutes. Last year’s MacBook Pro i7 finished the render in 35 minutes. Lee’s i9 took almost 40 minutes, a full four minutes more than last year’s model.

He then put the i9 in the freezer and ran the same render again. With some additional cooling, the new MacBook could render the scene in 27 minutes. “This degree of thermal throttling is not acceptable,” Lee said. “This isn’t something Apple should put out on the market and sell to people.”

CPUs run hot, especially when they’re performing intensive tasks. At high heats, the processors have to slow themselves down or risk damaging themselves. Engineers compensate for this by seating CPUs in a thermal compound designed to conduct heat away from the CPU and into heatsinks.

According to Lee, this is a known hardware issue with MacBooks and it comes down to a construction ethos that prizes thin and light laptops. “Traditionally, MacBooks don't have great thermal compound, they normally don't do a great job with it,” he told me via Skype. “But the issue this time around is that this particular CPU is very powerful. It's the type of CPU that you have in a two-inch thick gaming laptop. It's the type of CPU that literally the most powerful devices out there have and they're trying to put it into the MacBook chassis. From what I can see, they didn’t change the thermal design, didn’t engineer anything different physically. The fans are the same, the heat pipes are the same. It just can’t work.”

iFixit, a site that teaches people how to repair their own electronics, recently performed a teardown of the i7 model of the MacBook Pro. Other than the keyboard, iFixit found the inside of the MacBook Pro to be similar to previous models and gave the machine a repairability rating of 1.

Image: Cinebench results via redditor Aea.

Apple has advertised the new MacBook Pro to creative professionals and a powerful CPU is great for tasks such as Photoshop, CAD, and gaming. “I feel like [Apple] got pressured into putting that i9 into this device,” Lee told me. “ I think Intel made a really cool chip. I think consumers are interested in it. So maybe Apple felt some pressure from the market to be part of that.”

The MacBook Pro is still a great—if expensive—laptop. Just not the version with the i9. But Lee said it might not be completely hopeless. “One thing they could to, not to fix it but to address this and help it, by increasing the fan speed. There’s tweaks they could do software-wise to lower the temperature.”

It would help, but it wouldn’t fix the problem. Ultimately, the only way to get the current generation of i9s running to spec in a MacBook is to radically redesign the laptop’s chassis.

Apple did not immediately return our request for comment.