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macrumors 6502
Original poster
Nov 24, 2006
Los Angeles
Hey friends,

I have a 2019 16c Mac Pro that is maxed out even after a reset. Activity monitor isn't showing anything going crazy. The system is noticeably slower. Any ideas?



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Snow Tiger

macrumors 6502a
Dec 18, 2019
What devices are connected to your Mac ? And what third party PCIe expansion cards are installed ?

I once had a very similar situation with a Mac Pro 5,1 and a third party USB PCIe Card that had no driver support in macOS . The System was horribly sluggish ( 99 % loss of performance ) , all the CPU threads went to full load and Activity Monitor did not indicate any app was consuming significant resources . It was simply the System attempting to cope with unsatisfied driver requests being made by that expansion card .

Things went back to normal once the card was removed .

Sometimes an external USB Hub can cause an issue like this , too .


macrumors 6502
Dec 14, 2016

I just did a MacOS "refresh" - the PC rebooted itself at least three times, and it took nearly ten minutes. Interestingly, the Catalina version number remained at 10.15.4

It became available to me within the last hour, so it might not have reached you yet.

No idea whether it would help your problem, but may be worth a try...

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