Mojave (10.14.6) Coreaudiod full system freeze

Hi guys,

I've holded off posting this for a while, but I've not had any luck in fixing this myself nor managed to track down the root cause.

I was running Yosemite without any issues for a good few years. Saved up for a while and decided to upgrade everything. Started by installing 10.14.5 and eventually did a "vanilla" upgrade through System Update.

Audio will start cutting out or stuttering for a few seconds, and the entire system will slow to a crawl. Mouse lags, window animations stutter, any actions take eons to happen. The only way I can bring my system back is to have my terminal already open with sudo killall coreaudiod ready to be run. If I don't do this within about 15 seconds of the first audio stutter, the system will completely freeze up.

It only occurs when audio is playing (whether through videos via the browser, Spotify, or Ableton). When it happens, I've noticed that kernel_task will take up a lot of CPU. A bunch of error messages are spammed to the log, too:

kernel: (AppleUSBAudio) USB Sound assertion (Output Fell Behind) in /BuildRoot/Library/Caches/com.apple.xbs/Sources/AppleUSBAudio/AppleUSBAudio-315.6/AppleUSBAudioDevice.cpp at line 6507 powerd: [powerd:assertions] Process coreaudiod.144 TurnedOff PreventUserIdleSystemSleep "com.apple.audio.~:AMS2_Aggregate:0.context.preventuseridlesleep" age:01:12:01 id:4295000363 [System: DeclUser IntPrevDisp kDisp] coreaudiod: [com.apple.coreaudio:AudioHAL_Server] HALS_OverloadMessage.cpp:165:perform: Audio IO Overload inputs: 'AppleUSBAudioEngine:Focusrite:Scarlett 4i4 USB:TWE5D:1,2' outputs: 'AppleUSBAudioEngine:Focusrite:Scarlett 4i4 USB:TWE5D:1,2' cause: 'Unknown' prewarming: no recovering: no coreaudiod: [com.apple.coreaudio:AudioHAL_Server] HALS_IOA1Engine.cpp:365:EndWriting: HALS_IOA1Engine::EndWriting: got an error from the kernel trap, Error: 0xE00002D7 

This has been happening since I built this machine, on 10.14.5 as well as 10.14.6, and was happening before I starting using the Focusrite 4i4.

Things I've tried:

• Installing 10.14.5 afresh, on newly-formatted SSD.
• Mapping USB ports
• Using onboard audio with AppleALC (various layout-ids, but eventually settled on 11)
• Enabling iGPU and setting SMBIOS to iMac19,1 (started on this config, recently switched to disabled iGPU and iMacPro1,1)
• DisableIoMapper = true
• Setting NVRAM variable epid_provisioned=%01%00%00%00 under 8be4df61-93ca-11d2-aa0d-00e098032b8c (from here)

Specs:

• OpenCore 0.5.0
• i9-9900k
• Radeon VII (AMD)
• Gigabyte Z390 Designare
• 32GB RAM
• 2TB SSD macOS boot drive (+ many other drives!)
• Focusrite Saffire 4i4

ACPI:

• SSDT-DESIGNARE-Z390-NO-CNVW.aml
• SSDT-DTPG.aml
• SSDT-EC.aml
• SSDT-UIAC.aml
• SSDT-USBX.aml
• SSDT-Z390-DESIGNARE-TB3HP-V4.aml

Drivers:

• ApfsDriverLoader.efi
• AppleGenericInput.efi
• FwRuntimeServices.efi
• VBoxHfs.efi
• VirtualSmc.efi

Kexts:

• Lilu 1.3.8
• Whatevergreen 1.3.2
• AppleALC 1.4.1 (disabled)
• SmallTreeIntel82576 1.0
• SMCProcessor 1.0.7
• SMCSuperIO 1.0.7
• VirtualSMC 1.0.7
• IntelMausiEthernet 1.0.2
• USBPorts (mapped)

Other:

• SMBIOS: iMacPro1,1
• iGPU disabled in bios
• Audio stack disabled in bios
• Used this guide as a starting point.

OpenCore Config: https://pastebin.com/xM7uhyqL (serials and stuff like that removed)

Anyone else getting this? I'm at my wits end with it, just want a stable machine before I go about setting up iMessage, etc.