iMac 2017 MCA Error - replace i7?

[shreedx]

Hello guys,

I have an iMac (Retina 5K, 27-inch, 2017) with an i5 processor. I keep facing random reboots and reboot loops, that once I boot up end up in the error listed below.

I keep working around this issue by setting nvram boot params to cpu=2, which disables 3th and 4th cpu core and that gets me unstuck from the boot loop. This makes me think that the CPU itself might be damaged, but I don't know that for sure. If it is the case though, I should be able to swap it out for i7-7700k without any issues, right?

Or does this error seem to point to different issue (like something with motherboard) and I should just stick to this 2/4 cpu cores setup? Thanks!

*** MCA Error Report ***
CPU Machine Check Architecture Error Dump (CPU: Intel(R) Core(TM) i5-7600K CPU @ 3.80GHz, CPUID: 0x906E9)
CATERR detected! No MCA data found.


*** Device Tree ***
{
"pcie_cfg_base" : "0xe0000000",
"pci_devices" :
{
"0x0" : "MCHC@0",
"0x8000" : "PEG0@1",
"0x10000" : "IGPU@2",
"0x100000" : "PEG0@1/IOPP/GFX0@0",
"0xa0000" : "XHC1@14",
"0x101000" : "PEG0@1/IOPP/HDAU@0,1",
"0xb0000" : "IMEI@16",
"0xb8000" : "SATA@17",
"0xd8000" : "RP17@1B",
"0x200000" : "RP17@1B/IOPP/SSD0@0",
"0xe0000" : "RP01@1C",
"0xe1000" : "RP02@1C,1",
"0xe4000" : "RP05@1C,4",
"0xf8000" : "LPCB@1F",
"0xfa000" : "PMCR@1F,2",
"0xfb000" : "HDEF@1F,3",
"0xfc000" : "SBUS@1F,4",
"0x300000" : "RP01@1C/IOPP/ARPT@0",
"0x400000" : "RP02@1C,1/IOPP/GIGE@0",
"0x401000" : "RP02@1C,1/IOPP/SDXC@0,1",
"0x500000" : "RP05@1C,4/IOPP/UPSB@0",
"0x600000" : "RP05@1C,4/IOPP/UPSB@0/IOPP/DSB0@0",
"0x608000" : "RP05@1C,4/IOPP/UPSB@0/IOPP/DSB1@1",
"0x610000" : "RP05@1C,4/IOPP/UPSB@0/IOPP/DSB2@2",
"0x620000" : "RP05@1C,4/IOPP/UPSB@0/IOPP/DSB4@4",
"0x800000" : "RP05@1C,4/IOPP/UPSB@0/IOPP/DSB0@0/IOPP/NHI0@0",
"0x700000" : "RP05@1C,4/IOPP/UPSB@0/IOPP/DSB2@2/IOPP/XHC2@0"
},
"device_mmio" :
{
"PCI0@0" :
[
{ "a" : "0xcf8", "s" : "0x8" }
],
"PCI0@0/AppleACPIPCI/PEG0@1/IOPP/GFX0@0" :
[
{ "a" : "0x4000000000", "s" : "0x10000000" },
{ "a" : "0x4010000000", "s" : "0x200000" },
{ "a" : "0x92600000", "s" : "0x40000" },
{ "a" : "0x92640000", "s" : "0x20000" }
],
"PCI0@0/AppleACPIPCI/PEG0@1/IOPP/HDAU@0,1" :
[
{ "a" : "0x92660000", "s" : "0x4000" }
],
"PCI0@0/AppleACPIPCI/IGPU@2" :
[
{ "a" : "0x4011000000", "s" : "0x1000000" },
{ "a" : "0x4020000000", "s" : "0x10000000" }
],
"PCI0@0/AppleACPIPCI/XHC1@14" :
[
{ "a" : "0x4010310000", "s" : "0x10000" }
],
"PCI0@0/AppleACPIPCI/IMEI@16" :
[
{ "a" : "0x4010324000", "s" : "0x1000" }
],
"PCI0@0/AppleACPIPCI/SATA@17" :
[
{ "a" : "0x92728000", "s" : "0x2000" },
{ "a" : "0x9272c000", "s" : "0x100" },
{ "a" : "0x9272b800", "s" : "0x800" }
],
"PCI0@0/AppleACPIPCI/RP17@1B/IOPP/SSD0@0" :
[
{ "a" : "0x92500000", "s" : "0x4000" }
],
"PCI0@0/AppleACPIPCI/RP01@1C/IOPP/ARPT@0" :
[
{ "a" : "0x92400000", "s" : "0x8000" },
{ "a" : "0x92000000", "s" : "0x400000" }
],
"PCI0@0/AppleACPIPCI/RP02@1C,1/IOPP/GIGE@0" :
[
{ "a" : "0x4010200000", "s" : "0x10000" },
{ "a" : "0x4010210000", "s" : "0x10000" }
],
"PCI0@0/AppleACPIPCI/RP02@1C,1/IOPP/SDXC@0,1" :
[
{ "a" : "0x4010220000", "s" : "0x10000" }
],
"PCI0@0/AppleACPIPCI/RP05@1C,4/IOPP/UPSB@0/IOPP/DSB0@0/IOPP/NHI0@0" :
[
{ "a" : "0x92900000", "s" : "0x40000" },
{ "a" : "0x92940000", "s" : "0x1000" }
],
"PCI0@0/AppleACPIPCI/RP05@1C,4/IOPP/UPSB@0/IOPP/DSB2@2/IOPP/XHC2@0" :
[
{ "a" : "0x92800000", "s" : "0x10000" }
],
"PCI0@0/AppleACPIPCI/PMCR@1F,2" :
[
{ "a" : "0x92724000", "s" : "0x4000" }
],
"PCI0@0/AppleACPIPCI/HDEF@1F,3" :
[
{ "a" : "0x4010320000", "s" : "0x4000" },
{ "a" : "0x4010300000", "s" : "0x10000" }
],
"PCI0@0/AppleACPIPCI/SBUS@1F,4" :
[
{ "a" : "0x4010325000", "s" : "0x100" }
],
"DMAC" :
[
{ "a" : "0x0", "s" : "0x20" },
{ "a" : "0x81", "s" : "0x11" },
{ "a" : "0x93", "s" : "0xd" },
{ "a" : "0xc0", "s" : "0x20" }
],
"FWHD" :
[
{ "a" : "0xff000000", "s" : "0x1000000" }
],
"IPIC" :
[
{ "a" : "0x20", "s" : "0x2" },
{ "a" : "0x24", "s" : "0x2" },
{ "a" : "0x28", "s" : "0x2" },
{ "a" : "0x2c", "s" : "0x2" },
{ "a" : "0x30", "s" : "0x2" },
{ "a" : "0x34", "s" : "0x2" },
{ "a" : "0x38", "s" : "0x2" },
{ "a" : "0x3c", "s" : "0x2" },
{ "a" : "0xa0", "s" : "0x2" },
{ "a" : "0xa4", "s" : "0x2" },
{ "a" : "0xa8", "s" : "0x2" },
{ "a" : "0xac", "s" : "0x2" },
{ "a" : "0xb0", "s" : "0x2" },
{ "a" : "0xb4", "s" : "0x2" },
{ "a" : "0xb8", "s" : "0x2" },
{ "a" : "0xbc", "s" : "0x2" },
{ "a" : "0x4d0", "s" : "0x2" }
],
"MATH" :
[
{ "a" : "0xf0", "s" : "0x1" }
],
"LDRC" :
[
{ "a" : "0x2e", "s" : "0x2" },
{ "a" : "0x4e", "s" : "0x2" },
{ "a" : "0x61", "s" : "0x1" },
{ "a" : "0x63", "s" : "0x1" },
{ "a" : "0x65", "s" : "0x1" },
{ "a" : "0x67", "s" : "0x1" },
{ "a" : "0x80", "s" : "0x1" },
{ "a" : "0x92", "s" : "0x1" },
{ "a" : "0xb2", "s" : "0x2" },
{ "a" : "0xffff", "s" : "0x1" },
{ "a" : "0x1800", "s" : "0xff" },
{ "a" : "0x800", "s" : "0x80" }
],
"RTC" :
[
{ "a" : "0x70", "s" : "0x8" }
],
"TIMR" :
[
{ "a" : "0x40", "s" : "0x4" },
{ "a" : "0x50", "s" : "0x4" }
],
"SMC" :
[
{ "a" : "0x300", "s" : "0x20" },
{ "a" : "0xfef00000", "s" : "0x10000" }
],
"EC" :
[
{ "a" : "0x62", "s" : "0x1" },
{ "a" : "0x66", "s" : "0x1" }
],
"PDRC" :
[
{ "a" : "0xfed10000", "s" : "0x8000" },
{ "a" : "0xfed18000", "s" : "0x1000" },
{ "a" : "0xfed19000", "s" : "0x1000" },
{ "a" : "0xe0000000", "s" : "0x10000000" },
{ "a" : "0xfed20000", "s" : "0x20000" },
{ "a" : "0xfed90000", "s" : "0x4000" },
{ "a" : "0xfed45000", "s" : "0x4b000" },
{ "a" : "0xff000000", "s" : "0x1000000" },
{ "a" : "0xfee00000", "s" : "0x100000" },
{ "a" : "0xfd000000", "s" : "0x1000000" },
{ "a" : "0xfe000000", "s" : "0x10000" },
{ "a" : "0xfe010000", "s" : "0x1000" },
{ "a" : "0xfe020000", "s" : "0x16000" },
{ "a" : "0xfe036000", "s" : "0x6000" },
{ "a" : "0xfe03c000", "s" : "0x1000" },
{ "a" : "0xfe03d000", "s" : "0x83000" },
{ "a" : "0xfe0c0000", "s" : "0x40000" },
{ "a" : "0xfe100000", "s" : "0x100000" },
{ "a" : "0xfe200000", "s" : "0x200000" },
{ "a" : "0xfe400000", "s" : "0x10000" },
{ "a" : "0xfe410000", "s" : "0x1f0000" },
{ "a" : "0xfe600000", "s" : "0x200000" }
]
}
}

 

[barbu]

I don’t think your cpu has problems. I really don’t think you can swap processors, I am pretty sure they are soldered in. It’s probably your power supply.

 

[Andy5Kimac]

I don’t think your cpu has problems. I really don’t think you can swap processors, I am pretty sure they are soldered in. It’s probably your power supply.

incorrect. A lot of ppl mistaken the GPU for the CPU in this model iMac. I recall OWC tear down YouTube video on the 2017 5k iMac they mistaken the soldered GPU as the CPU.

Anyhow I just recently upgraded my 2017 27" iMac i5 7600K version to the i7 7700K. I can confirm CPU is not soldered. I followed ifixit's DIY guide here.

https://www.ifixit.com/Guide/iMac+Intel+27-Inch+Retina+5K+Display+CPU+Replacement/30515

OP you shouldn't have any issues upgrading to i7 7700k from your i5. Theres also tons of YouTube videos on others who upgraded their 2017 27" i5 iMac's to i7 7700k as well. Good luck

 

[The_Croupier]

I'd be checking your ram modules and reinstall of the OS, maybe some extensions got corrupted.

 

[barbu]

incorrect. A lot of ppl mistaken the GPU for the CPU in this model iMac. I recall OWC tear down YouTube video on the 2017 5k iMac they mistaken the soldered GPU as the CPU.

Anyhow I just recently upgraded my 2017 27" iMac i5 7600K version to the i7 7700K. I can confirm CPU is not soldered. I followed ifixit's DIY guide here.

https://www.ifixit.com/Guide/iMac+Intel+27-Inch+Retina+5K+Display+CPU+Replacement/30515

OP you shouldn't have any issues upgrading to i7 7700k from your i5. Theres also tons of YouTube videos on others who upgraded their 2017 27" i5 iMac's to i7 7700k as well. Good luck

Fair enough, but I still don’t think that’s the problem.

 

[shreedx]

Fair enough, but I still don’t think that’s the problem.

I know for sure it is, as I've used to be stuck in the boot loop until I somehow managed to boot once and set boot-args="cpus=2" which technically disabled cores #3 and #4.

 

[barbu]

Yeah I caught that but I still suspect power instability. But I guess you could try a new chip and see what happens?