I have a 2015 27" iMac running Catalina, i have just put in a SSD as i had the flashing "?" with the HD running Big Sur, i tried to install Big Sur but it wouldn't load so i have installed Catalina, now the iMac reboots for no reason i get a message that the computer quit unexpectedly and will restart, there is no extra software installed and nothing connected via usb, everything works as it should and is up to speed it just shuts down could it be the PSU
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2015 iMac rebooting randomly
- Thread starter thewall
- Start date
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Run Apple Diagnostics
support.apple.com
Use Apple Diagnostics to test your Mac - Apple Support
Apple Diagnostics, formerly known as Apple Hardware Test, can check your Mac for hardware issues.
PSU no, SSD, maybe. Check the SMART status for the SSD, that should tell you whether the SSD's internal diagnostics are reporting any issues.
You can download DriveDx trial version
DriveDx - the most advanced drive health diagnostics and monitoring utility
DriveDx - the most advanced drive health (S.M.A.R.T.) diagnostics and monitoring utility. Save yourself the data loss and downtime that is associated with unexpected SSD and HDD failures. Don't worry about losing your important data, music, and photographs.
binaryfruit.com
Can anybody make sense of this, this is the report "your computer restared because of a problem"
panic(cpu 0 caller 0xffffff8004813767): "AppleAHCIDiskQueueManager::setPowerState(0xffffff8035a2a480 : 0xffffff7f86fd25d2, 3 -> 2) timed out after 100846 ms"@/AppleInternal/BuildRoot/Library/Caches/com.apple.xbs/Sources/xnu/xnu-6153.141.66/iokit/Kernel/IOServicePM.cpp:5296
Backtrace (CPU 0), Frame : Return Address
0xffffff9ad83b3b40 : 0xffffff800411b54d
0xffffff9ad83b3b90 : 0xffffff8004255d85
0xffffff9ad83b3bd0 : 0xffffff800424790e
0xffffff9ad83b3c20 : 0xffffff80040c1a40
0xffffff9ad83b3c40 : 0xffffff800411ac17
0xffffff9ad83b3d40 : 0xffffff800411b007
0xffffff9ad83b3d90 : 0xffffff80048c03bc
0xffffff9ad83b3e00 : 0xffffff8004813767
0xffffff9ad83b3e50 : 0xffffff8004813049
0xffffff9ad83b3e60 : 0xffffff800482a5de
0xffffff9ad83b3ea0 : 0xffffff8004811df8
0xffffff9ad83b3ec0 : 0xffffff800415d525
0xffffff9ad83b3f40 : 0xffffff800415d051
0xffffff9ad83b3fa0 : 0xffffff80040c113e
BSD process name corresponding to current thread: kernel_task
Mac OS version:
19H2026
Kernel version:
Darwin Kernel Version 19.6.0: Tue Jun 21 21:18:39 PDT 2022; root:xnu-6153.141.66~1/RELEASE_X86_64
Kernel UUID: D5630E55-7695-313B-B468-6347805B0B6F
Kernel slide: 0x0000000003e00000
Kernel text base: 0xffffff8004000000
__HIB text base: 0xffffff8003f00000
System model name: iMac15,1 (Mac-42FD25EABCABB274)
System shutdown begun: NO
Panic diags file available: YES (0x0)
System uptime in nanoseconds: 1555797464720
last loaded kext at 70632571268: >!A!BMultitouch 97 (addr 0xffffff7f88a8e000, size 53248)
last unloaded kext at 65457429878: >!A!ILpssGspi 3.0.60 (addr 0xffffff7f8744d000, size 45056)
loaded kexts:
>!A!BMultitouch 97
>AudioAUUC 1.70
@fileutil 20.036.15
@filesystems.autofs 3.0
>!AMikeyHIDDriver 131
>!AMikeyDriver 283.15
>!AHDA 283.15
>AGPM 111.4.4
>!APlatformEnabler 2.7.0d0
>X86PlatformShim 1.0.0
>!AUpstreamUserClient 3.6.8
@kext.AMDFramebuffer 3.1.0
@kext.AMDRadeonX4000 3.1.0
@kext.AMDRadeonServiceManager 3.1.0
>!AGraphicsDevicePolicy 5.2.7
@AGDCPluginDisplayMetrics 5.2.7
>!AHV 1
|IOUserEthernet 1.0.1
|IO!BSerialManager 7.0.6f8
>!A!IHD5000Graphics 14.0.7
>!AThunderboltIP 3.1.4
>eficheck 1
>!ALPC 3.1
>pmtelemetry 1
>!ASMCLMU 212
@Dont_Steal_Mac_OS_X 7.0.0
>!A!IFramebufferAzul 14.0.7
>!A!ISlowAdaptiveClocking 4.0.0
@kext.AMD7000!C 3.1.0
>!AMCCSControl 1.14
>!AVirtIO 1.0
@filesystems.hfs.kext 522.100.6
@!AFSCompression.!AFSCompressionTypeDataless 1.0.0d1
@BootCache 40
@!AFSCompression.!AFSCompressionTypeZlib 1.0.0
@filesystems.apfs 1412.141.3
@private.KextAudit 1.0
>AirPort.BrcmNIC 1400.1.1
>!ASDXC 1.7.7
|!ABCM5701Ethernet 10.3.5
>!AAHCIPort 341.140.1
>!ARTC 2.0
>!AACPIButtons 6.1
>!AHPET 1.8
>!ASMBIOS 2.1
>!AACPIEC 6.1
>!AAPIC 1.7
$!AImage4 1
@nke.applicationfirewall 303
$TMSafetyNet 8
@!ASystemPolicy 2.0.0
|EndpointSecurity 1
>!AMultitouchDriver 3440.1.1
>!AInputDeviceSupport 3440.8
>!A!BHIDKeyboard 209
>IO!BHIDDriver 7.0.6f8
>!AHIDKeyboard 209
@kext.triggers 1.0
>DspFuncLib 283.15
@kext.OSvKernDSPLib 529
@kext.AMDRadeonX4030HWLibs 1.0
@kext.AMDRadeonX4000HWServices 3.1.0
>!AGraphicsControl 5.2.7
|IOAVB!F 850.1
>!AThunderboltEDMSink 4.2.3
|IONDRVSupport 576.2
|IOAccelerator!F2 438.7.4
>!AHDA!C 283.15
|IOHDA!F 283.15
@!AGPUWrangler 5.2.7
|IOSlowAdaptiveClocking!F 1.0.0
>X86PlatformPlugin 1.0.0
>IOPlatformPlugin!F 6.0.0d8
@kext.AMDSupport 3.1.0
@!AGraphicsDeviceControl 5.2.7
>!ASMBus!C 1.0.18d1
|IOGraphics!F 576.2
>!ASMBusPCI 1.0.14d1
@plugin.IOgPTPPlugin 840.3
|Broadcom!BHost!CUSBTransport 7.0.6f8
|IO!BHost!CUSBTransport 7.0.6f8
|IO!BHost!CTransport 7.0.6f8
|IO!B!F 7.0.6f8
|IO!BPacketLogger 7.0.6f8
>usb.!UHub 1.2
>usb.networking 5.0.0
>usb.!UHostCompositeDevice 1.2
|IOAudio!F 300.2
@vecLib.kext 1.2.0
|IOSerial!F 11
|IOSurface 269.11
@filesystems.hfs.encodings.kext 1
>!AXsanScheme 3
>!AThunderboltDPOutAdapter 6.2.6
>!AThunderboltDPInAdapter 6.2.6
>!AThunderboltDPAdapter!F 6.2.6
>!AThunderboltPCIDownAdapter 2.5.4
>!AThunderboltNHI 5.8.6
|IOThunderbolt!F 7.6.1
|IOAHCIBlock!S 316.100.5
|IO80211!F 1200.12.2b1
>corecapture 1.0.4
|IOSkywalk!F 1
|IOUSB!F 900.4.2
|IOEthernetAVB!C 1.1.0
>mDNSOffloadUserClient 1.0.1b8
|IOAHCI!F 290.0.1
>usb.!UXHCIPCI 1.2
>usb.!UXHCI 1.2
>!AEFINVRAM 2.1
>!AEFIRuntime 2.1
|IOSMBus!F 1.1
|IOHID!F 2.0.0
$quarantine 4
$sandbox 300.0
@Kext.!AMatch 1.0.0d1
>DiskImages 493.0.0
>!AFDEKeyStore 28.30
>!AEffaceable!S 1.0
>!ASSE 1.0
>!AKeyStore 2
>!UTDM 489.120.1
|IOSCSIBlockCommandsDevice 422.120.3
>!ACredentialManager 1.0
>KernelRelayHost 1
>!ASEPManager 1.0.1
>IOSlaveProcessor 1
|IOUSBMass!SDriver 157.140.1
|IOSCSIArchitectureModel!F 422.120.3
|IO!S!F 2.1
|IOUSBHost!F 1.2
>!UHostMergeProperties 1.2
>usb.!UCommon 1.0
>!ABusPower!C 1.0
|CoreAnalytics!F 1
>!AMobileFileIntegrity 1.0.5
@kext.CoreTrust 1
|IOTimeSync!F 840.3
|IONetworking!F 3.4
|IOReport!F 47
>!AACPIPlatform 6.1
>!ASMC 3.1.9
>watchdog 1
|IOPCI!F 2.9
|IOACPI!F 1.4
@kec.pthread 1
@kec.corecrypto 1.0
@kec.Libm 1
panic(cpu 0 caller 0xffffff8004813767): "AppleAHCIDiskQueueManager::setPowerState(0xffffff8035a2a480 : 0xffffff7f86fd25d2, 3 -> 2) timed out after 100846 ms"@/AppleInternal/BuildRoot/Library/Caches/com.apple.xbs/Sources/xnu/xnu-6153.141.66/iokit/Kernel/IOServicePM.cpp:5296
Backtrace (CPU 0), Frame : Return Address
0xffffff9ad83b3b40 : 0xffffff800411b54d
0xffffff9ad83b3b90 : 0xffffff8004255d85
0xffffff9ad83b3bd0 : 0xffffff800424790e
0xffffff9ad83b3c20 : 0xffffff80040c1a40
0xffffff9ad83b3c40 : 0xffffff800411ac17
0xffffff9ad83b3d40 : 0xffffff800411b007
0xffffff9ad83b3d90 : 0xffffff80048c03bc
0xffffff9ad83b3e00 : 0xffffff8004813767
0xffffff9ad83b3e50 : 0xffffff8004813049
0xffffff9ad83b3e60 : 0xffffff800482a5de
0xffffff9ad83b3ea0 : 0xffffff8004811df8
0xffffff9ad83b3ec0 : 0xffffff800415d525
0xffffff9ad83b3f40 : 0xffffff800415d051
0xffffff9ad83b3fa0 : 0xffffff80040c113e
BSD process name corresponding to current thread: kernel_task
Mac OS version:
19H2026
Kernel version:
Darwin Kernel Version 19.6.0: Tue Jun 21 21:18:39 PDT 2022; root:xnu-6153.141.66~1/RELEASE_X86_64
Kernel UUID: D5630E55-7695-313B-B468-6347805B0B6F
Kernel slide: 0x0000000003e00000
Kernel text base: 0xffffff8004000000
__HIB text base: 0xffffff8003f00000
System model name: iMac15,1 (Mac-42FD25EABCABB274)
System shutdown begun: NO
Panic diags file available: YES (0x0)
System uptime in nanoseconds: 1555797464720
last loaded kext at 70632571268: >!A!BMultitouch 97 (addr 0xffffff7f88a8e000, size 53248)
last unloaded kext at 65457429878: >!A!ILpssGspi 3.0.60 (addr 0xffffff7f8744d000, size 45056)
loaded kexts:
>!A!BMultitouch 97
>AudioAUUC 1.70
@fileutil 20.036.15
@filesystems.autofs 3.0
>!AMikeyHIDDriver 131
>!AMikeyDriver 283.15
>!AHDA 283.15
>AGPM 111.4.4
>!APlatformEnabler 2.7.0d0
>X86PlatformShim 1.0.0
>!AUpstreamUserClient 3.6.8
@kext.AMDFramebuffer 3.1.0
@kext.AMDRadeonX4000 3.1.0
@kext.AMDRadeonServiceManager 3.1.0
>!AGraphicsDevicePolicy 5.2.7
@AGDCPluginDisplayMetrics 5.2.7
>!AHV 1
|IOUserEthernet 1.0.1
|IO!BSerialManager 7.0.6f8
>!A!IHD5000Graphics 14.0.7
>!AThunderboltIP 3.1.4
>eficheck 1
>!ALPC 3.1
>pmtelemetry 1
>!ASMCLMU 212
@Dont_Steal_Mac_OS_X 7.0.0
>!A!IFramebufferAzul 14.0.7
>!A!ISlowAdaptiveClocking 4.0.0
@kext.AMD7000!C 3.1.0
>!AMCCSControl 1.14
>!AVirtIO 1.0
@filesystems.hfs.kext 522.100.6
@!AFSCompression.!AFSCompressionTypeDataless 1.0.0d1
@BootCache 40
@!AFSCompression.!AFSCompressionTypeZlib 1.0.0
@filesystems.apfs 1412.141.3
@private.KextAudit 1.0
>AirPort.BrcmNIC 1400.1.1
>!ASDXC 1.7.7
|!ABCM5701Ethernet 10.3.5
>!AAHCIPort 341.140.1
>!ARTC 2.0
>!AACPIButtons 6.1
>!AHPET 1.8
>!ASMBIOS 2.1
>!AACPIEC 6.1
>!AAPIC 1.7
$!AImage4 1
@nke.applicationfirewall 303
$TMSafetyNet 8
@!ASystemPolicy 2.0.0
|EndpointSecurity 1
>!AMultitouchDriver 3440.1.1
>!AInputDeviceSupport 3440.8
>!A!BHIDKeyboard 209
>IO!BHIDDriver 7.0.6f8
>!AHIDKeyboard 209
@kext.triggers 1.0
>DspFuncLib 283.15
@kext.OSvKernDSPLib 529
@kext.AMDRadeonX4030HWLibs 1.0
@kext.AMDRadeonX4000HWServices 3.1.0
>!AGraphicsControl 5.2.7
|IOAVB!F 850.1
>!AThunderboltEDMSink 4.2.3
|IONDRVSupport 576.2
|IOAccelerator!F2 438.7.4
>!AHDA!C 283.15
|IOHDA!F 283.15
@!AGPUWrangler 5.2.7
|IOSlowAdaptiveClocking!F 1.0.0
>X86PlatformPlugin 1.0.0
>IOPlatformPlugin!F 6.0.0d8
@kext.AMDSupport 3.1.0
@!AGraphicsDeviceControl 5.2.7
>!ASMBus!C 1.0.18d1
|IOGraphics!F 576.2
>!ASMBusPCI 1.0.14d1
@plugin.IOgPTPPlugin 840.3
|Broadcom!BHost!CUSBTransport 7.0.6f8
|IO!BHost!CUSBTransport 7.0.6f8
|IO!BHost!CTransport 7.0.6f8
|IO!B!F 7.0.6f8
|IO!BPacketLogger 7.0.6f8
>usb.!UHub 1.2
>usb.networking 5.0.0
>usb.!UHostCompositeDevice 1.2
|IOAudio!F 300.2
@vecLib.kext 1.2.0
|IOSerial!F 11
|IOSurface 269.11
@filesystems.hfs.encodings.kext 1
>!AXsanScheme 3
>!AThunderboltDPOutAdapter 6.2.6
>!AThunderboltDPInAdapter 6.2.6
>!AThunderboltDPAdapter!F 6.2.6
>!AThunderboltPCIDownAdapter 2.5.4
>!AThunderboltNHI 5.8.6
|IOThunderbolt!F 7.6.1
|IOAHCIBlock!S 316.100.5
|IO80211!F 1200.12.2b1
>corecapture 1.0.4
|IOSkywalk!F 1
|IOUSB!F 900.4.2
|IOEthernetAVB!C 1.1.0
>mDNSOffloadUserClient 1.0.1b8
|IOAHCI!F 290.0.1
>usb.!UXHCIPCI 1.2
>usb.!UXHCI 1.2
>!AEFINVRAM 2.1
>!AEFIRuntime 2.1
|IOSMBus!F 1.1
|IOHID!F 2.0.0
$quarantine 4
$sandbox 300.0
@Kext.!AMatch 1.0.0d1
>DiskImages 493.0.0
>!AFDEKeyStore 28.30
>!AEffaceable!S 1.0
>!ASSE 1.0
>!AKeyStore 2
>!UTDM 489.120.1
|IOSCSIBlockCommandsDevice 422.120.3
>!ACredentialManager 1.0
>KernelRelayHost 1
>!ASEPManager 1.0.1
>IOSlaveProcessor 1
|IOUSBMass!SDriver 157.140.1
|IOSCSIArchitectureModel!F 422.120.3
|IO!S!F 2.1
|IOUSBHost!F 1.2
>!UHostMergeProperties 1.2
>usb.!UCommon 1.0
>!ABusPower!C 1.0
|CoreAnalytics!F 1
>!AMobileFileIntegrity 1.0.5
@kext.CoreTrust 1
|IOTimeSync!F 840.3
|IONetworking!F 3.4
|IOReport!F 47
>!AACPIPlatform 6.1
>!ASMC 3.1.9
>watchdog 1
|IOPCI!F 2.9
|IOACPI!F 1.4
@kec.pthread 1
@kec.corecrypto 1.0
@kec.Libm 1
I was having all kinds of problem with my iMac 27" until I clean installed MacOS on an external SSD and designated it as my boot drive.
Thanks I have installed OS many times, when the HD sort of failed ( Flashing ? ) so used an external SSD but had all sorts of problems sleeping and restarting and shutting down
@thewall
What the panic is telling us (plain English)
The key line is:AppleAHCIDiskQueueManager::setPowerState(..., 3 -> 2) timed out after 100846 ms
- AppleAHCIDiskQueueManager is the driver managing AHCI/SATA storage (internal spinning HDD, SATA SSD, or SATA portion of a Fusion Drive).
- It timed out trying to change the power state (usually on sleep, standby, or wake).
- When storage doesn’t respond to a power transition in time, macOS’s I/O Kit power management trips a kernel panic to protect the system.
Other corroborating bits:
- BSD process name: kernel_task (typical for power management panics).
- macOS version 19H2026 = macOS Catalina 10.15.7 (2022-06 supplemental).
- Loaded kexts include IOAHCIBlockStorage/AppleAHCIPort, which are normal for SATA storage.
Likely causes (most to least likely)
- Failing internal SATA drive (often the HDD half of a Fusion Drive) struggling to respond during sleep/wake.
- SATA cable/connector issues (less common in iMacs than MacBooks, but still possible).
- An external USB/SATA storage device not handling power transitions well.
- Sleep settings or a rare kext interaction—but your list looks stock/Apple.
What I’d do—prioritized checklist
0) Back up right now- If you’re not fully backed up, start Time Machine or clone the disk with Carbon Copy Cloner or SuperDuper!. A disk that times out on power changes can progress to outright I/O errors.
- Temporarily disconnect all external storage (USB, Thunderbolt, SD cards).
- See if the panic still occurs when the Mac sleeps/wakes.
- In System Preferences → Energy Saver, uncheck “Put hard disks to sleep when possible.”
- Also set “Computer sleep” to Never for testing (then manually sleep once to test wake).\This reduces power-state transitions that trigger the timeout.
- Disk Utility → First Aid on each internal volume and the physical disk.
- Check SMART status in Disk Utility (it will say “Verified” or show warnings).\If you want deeper SMART: third-party tools (like DriveDx) can show pending sectors/reallocated counts.
- Hold Shift on boot to enter Safe Mode. This trims nonessential kexts and rebuilds caches.\If panics stop in Safe Mode, it points more to software; if they persist, more likely hardware.
- Shut down. Power on and hold D (or Option‑D) to run Apple Diagnostics.\Note any reference codes (e.g., PPF for power, VFD for storage).
# View recent power management transitions
log show --predicate 'subsystem == "com.apple.iokit.IOPM"' --last 2d
# Filter for AHCI / BlockStorage warnings or I/O errors
log show --predicate '(process == "kernel") AND (eventMessage CONTAINS "AHCI" OR eventMessage CONTAINS "IOAHCI" OR eventMessage CONTAINS "I/O error")' --last 2d
Look for repeated I/O errors, long command timeouts, or sleep/wake failures.
7) SMC/PRAM reset
- SMC reset (for iMac): shut down, unplug power for 15 seconds, plug back in, wait 5 seconds, then power on.
- NVRAM/PRAM reset: power on and hold Option-Command-P-R ~20 seconds.
- Consider splitting the Fusion Drive or replacing the HDD. The spinning disk is usually the culprit.
- Practical path:
- Clone to an external SSD, boot from it, and see if panics stop.\If they do, replace internal storage (often with a single SATA SSD), then restore.
- Alternatively, keep running off an external Thunderbolt/USB‑C SSD.
- If storage tests good but panics persist, try a clean Catalina reinstall or upgrade path (Big Sur/Monterey if supported by your apps). Fresh OS removes any odd caches/configs—but given the AHCI power state timeout, hardware is still the leading suspect.
Why this matches your stack
- The backtrace goes through IOServicePM (IOServicePM.cpp:5296) into AppleAHCI devices during power transition—classic storage power management hang.
- Uptime ~1555 seconds (~26 minutes) before panic—often happens on first sleep or display sleep cycle after boot.
- Nothing in kext list screams third-party interference.
Quick triage questions for you
- Is this iMac using a Fusion Drive? (SSD + HDD).
- Do panics happen when waking from sleep or randomly during use?
- Any external drives or hubs connected when it happens?
- Have you noticed slow file access, beachballs, or I/O errors recently?
If your device did have a fusion drive, did you rebuild it after replacing the HDD?
Any Fusion Drives still in service should be regarded with extreme suspicion at this point.
I wouldn't rule out the SSD portion wearing out either. Apple used absurdly small SSDs for these, as small as 32 GB, and they got absolutely hammered with write cycles because data was constantly being copied to and from them as the system optimized using the SSD portion for files in active use. Use DriveDx to examine the volume (free version will work for this) and see what the wear levels on the SSD are.
This is what happened to my 2014 iMac 5K, and I ended up just replacing the SATA HDD with a SATA SSD and calling it a day. I left the all-but-dead blade SSD in place as they're a PITA to source and replace, apparently.
Fusion Drives were a great little hack back when SSDs were nosebleed expensive, but their time has definitely passed.
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Even if a fusion drive was fine, IMO the first troubleshooting step would be to replace any fusion drive, because this is 2025 and they are bad news now. Even if it has not failed yet, it will. So why risk data on a dinosaur fusion Drive?
I don’t think so I have installed a SSD
No wakes from sleep ok and randomly reboots
No external drives
When working works great slow to load on restart
It did have a Fusion Drive didn’t no you had to rebuild it, was told if I installed a SSD i wouldn’t need a Fusion
Does the logic board have a SSD on it is that the Fusion Drive
First time dismantling a iMac so everything is new to me
Run Apple diagnostics and Dx both came back clean
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Yes. Fusion Drive two components (SSD on logic board as fast cache + internal SATA HDD). If Fusion Drive fail, it is either SSD or HDD, more likely SSD after all this time. If you replace internal HDD w/ SATA SSD, you still have SSD on logic board. If SSD on logic board failing, it could still cause issues when macOS try to repair/mount/access failing SSD. It is recommended to
1) replace both SSD on logic board + internal SATA HDD w/ new SSD components
2) initialize each SSD as separate internal drives as fast cache no longer needed
3) NOT recreate Fusion Drive from two SSD components; unnecessary as fast cache no longer needed
This would be my recommendation as well @thewall do not rebuild the Fusion Drive, because it will only give you more problems in my experience. You can just wipe the Fusion SSD in Disk Utility, and you'll just have like an extra ~32GB on a seperate drive that you can keep all of your secrets on.
This was my next question do I look in DU for a drive that has about 32gb and erase it and would that stop the computer looking for it on startup
I have removed the PSU and had it tested and there is a faulty capacitor so that could also be the problem,
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