Some folks with external GPUs have run into trouble with the latest version of macOS 10.15 (Catalina), with serious problems encountered including Macs freezing and failing to boot up in some scenarios.
This issue was highlighted by Apple Insider, which noted that only certain external GPUs (or eGPUs – graphics cards in external enclosures) were affected. Reportedly it’s eGPUs that use Radeon 570 and 580 graphics cards which are running into trouble, with Mac mini users seemingly suffering the most at the hands of this macOS Catalina gremlin.
Sadly the problems are pretty nasty ones and include folks reporting that their Macs are freezing, or not booting up when a display is connected to the eGPU (or the Mac might start in the latter case, but then immediately restart).
It’s not clear what the root cause might be, and Apple hasn’t been drawn to comment yet, but the current most likely culprit seems to be the drivers for AMD’s Polaris graphics cards (the Radeon 570 and 580 are both Polaris).
It seems that Vega-based GPUs aren’t hit by this issue. Furthermore, it’s worth noting that some of the affected eGPUs are on Apple’s official list of supported products for suitable Thunderbolt 3 enclosures, which are recommended for certain graphics cards
Indeed, Apple Insider asserts that it has tested a Sonnet eGPU with a Sapphire 570 graphics card inside, finding issues present – and that particular all-in-one combo is recommended by Apple.
Hopefully whatever bugs are messing things around here will be ironed out soon enough.
Support for external GPUs was introduced back with macOS High Sierra (10.13.4) as a neat way to beef up the power of your MacBook (or indeed other Mac) via a Thunderbolt 3 port (with its chunky bandwidth).
Support has been considerably refined since, with a good deal of optimization work carried out in Catalina and before. However, the lack of official support for Nvidia graphics cards remains a serious sticking point for many folks.
Naturally, some bugs are to be expected in the new version of an operating system, and macOS Catalina has also reportedly been causing emails to go missing in some cases.