Apple's 2018 MacBook Pro has some serious CPU throttling issues (Updated)

On paper, Apple's new 15-inch MacBook Pro appears to be a monster of a laptop, configurable with a powerful Intel eighth-generation Core i9 six-core processor.

But it initial testing revealed shelling out an extra $400 to upgrade to the beefier CPU wasn't worth it. Benchmarks shared by customers who purchased the pricey processor boost revealed the chip was significantly throttled under heavy workloads with performance on-par with the base Intel Core i7 chip.

Apple has since released a new software update that fixes the CPU throttling.

Tech YouTuber Dave Lee was the first to call attention to the 2018 MacBook Pro's CPU throttling problems.

Though Lee didn't dispute the power of the Core i9 chip, which is unlocked, and can be overclocked for some serious raw performance, he took issue with the MacBook Pro's thin design, which limited the computer's cooling and peak performance.

"The problem is this chassis, the MacBook Pro, cannot cool the i9 properly," Lee says in his video. "When you look at renders, and I'm using Adobe Premiere, after a few seconds, we start to see some very serious throttling.

"This i9 in this MacBook Pro can't even maintain the base clock speed. Forget about [Turbo Boost] and all that stuff, it can't even maintain the 2.9GHz base clock, which is absurd. All of that CPU potential is wasted inside of this chassis."

Running Adobe Premiere, the 2018 MacBook Pro (Core i9) took 39 minutes to export a 5.5-minute 5K video to 4K resolution. In comparison, a 2017 MacBook Pro (Core i7) took 35 minutes. That's not a huge difference.

Lee blamed the similar performance between the old and new MBP on poor thermal cooling for the CPU. To prove it, he put the 2018 MBP in a freezer to better cool its i9 CPU, and wouldn't you know it, the same render process improved, dropping from 39 minutes to 27 minutes.

"This degree of thermal throttling is not acceptable," said Lee.

Lee's not alone in confirming the processor throttling. AppleInsider ran its own CPU-intensive tests, pitting a 2018 15-inch MacBook Pro with the base 2.2GHz Intel Core i7 processor ($2,400) against the 2.9GHz Core i9 model ($2,800) and concluded pretty much the same.

For its tests, AppleInsider used Cinebench R15, a CPU-intensive 3D rendering program, to compare performance between both machines.

As you can see in their video above, they ran several tests on both machines and noted the clock speeds and temperature. Despite having a maximum advertised Turbo Boost clock speed of 4.8GHz, the Core i9 MBP only mustered 4.1GHz and only for a second before quickly dropping down because of the increased temperature at the higher clock speed.

On average, the Core i9 MBP's clock speed fluctuated between 2.4-2.8GHz, which is below the machine's advertised 2.9GHz base speed.

Meanwhile, the same tests performed on the 2018 MBP with 2.2GHz Core i7 chip show the machine's able to maintain a clock speed of between 2.3-2.6GHz, just above its base speed.

As the clock speed dips and spikes, AppleInsider noticed the i9 MBP's fans couldn't keep up. They just didn't kick up fast enough to keep pace with cooling the processor as its clock speed increased.

Reddit user Artu Ergashev's ran his own independent tests between the Core i9 MBP and an older Core i7 MBP. His findings suggests Apple could be prioritizing low noise over performance.

Speaking with Motherboard, Lee said Apple could increase the fan speed with a software update, which would help better cool the Core i9 chip so it can maintain a consistent base clock speed and not overheat when overclocked.

UPDATE: July 24, 2018, 1:09 p.m. EDT Apple says the CPU throttling was caused by a software bug and affects all 2018 15-inch MacBook Pros. Updating to the latest software should fix the problem. The original story follows below.