Apple rushes out fix for MacBook performance throttling issue

Apple failed to sign digital key for part of its thermal management system firmware

Apple has claimed that extreme throttling issues on its latest MacBook - starting price £1,249 for a dual-core model with 128GB of SSD storage - is due to a missing digital key in the firmware. It has pledged to rush out a fix to users.

The missing digital signature in the thermal management system, meant that the cooling fans did not respond properly when the system was under load and, hence, running hot. This caused the CPU to throttle well below its standard clock speed to prevent meltdown.

Apple claims that it only discovered the mistake - its failure to digitally sign a part of its own device's firmware - after running tests in the wake of YouTube videos slating the performance of the new MacBooks.

The first of those tests by hardware enthusiast Dave Lee indicated that the MacBook struggled to render a benchmark Adobe Premiere video. The latest Intel Core i9-based MacBook Pro, according to Lee, rendered the benchmark video in 39 minutes and 37 seconds under ordinary conditions. But when placed in the freezer to keep it cool it rendered the same video in 27 minutes and 18 seconds.

However, both of those compare poorly to the same video being rendered on a Windows-based Gigabyte Aero 15X, which did it in seven minutes and 18 seconds.

The key to that big performance difference is that whereas the Apple MacBooks either use integrated Intel Iris Plus Graphics (640 or 655) or a low-end AMD Radeon Pro (555X or 560X), the Gigabyte bears a vastly more powerful Nvidia GTX 1070 GPU.

In a statement, Apple claimed: "Following extensive performance testing under numerous workloads, we've identified that there is a missing digital key in the firmware that impacts the thermal management system and could drive clock speeds down under heavy thermal loads on the new MacBook Pro."

A bug fix was rushed out in Apple's MacOS High Sierra 10.13.6 Supplemental Update yesterday.

The company added: "We apologise to any customer who has experienced less than optimal performance on their new systems. Customers can expect the new 15-inch MacBook Pro to be up to 70 per cent faster, and the 13-inch MacBook Pro with Touch Bar to be up to two times faster, as shown in the performance results on our website."