crashing after install

[smintel]

I managed to get el capitan running fine last night, then this morning when I tried to boot I started getting ' P-State Stepper Error 18' error. Odd as I wasn't having this problem before.

My BIOS (f10) doesn't appear to have a setting for EIST, so unable to do the fix in list of solutions, however I changed system profile from MacPro 3,1 to iMac 13,1 as suggested in one of the comments - and this worked in as far as I was able boot into el capitan and everything looked fine.. However after about 30 seconds computer crashes and restarts without warning.

Rolling back to my Yosemite backup for now, but any thoughts on how this might be resolved would be appreciated!

 

[ammulder]

Are you booting with cpus=1 or NullCPUPowerManagement.kext, or better yet have you generated and installed an SSDT for your CPU?

Have you installed Nvidia Web drivers?

 

[smintel]

I have installed Nvidia web drivers, but haven't tried cpus=1, the kext or SSDT.. will look into thanks. Is using MaciASL the best way to generate SSDTs?

Are these either/or options or do I need to do all?

 

[n3oNLit3]

The Native CPU PM kext gets created through using ssdtPRGen.sh command. See here http://www.tonymacx86.com/mavericks...vericks-native-cpu-igpu-power-management.html for more information on how to use the script and get Native CPU PM workiing.

 

[ammulder]

• cpus=1 is just a temporary workaround (disables all but one core)
• NullCPUPowerManagement.kext may get you running, but with mediocre, poor, or absent CPU power management. Maybe you don't care.
• Generating an SSDT with the tools and procedure n3oNLit3 pointed you to is the best approach.

 

[smintel]

Thanks - I had a go at generating a SDDT for my CPU but it didn't seem to work - I ran the script, and placed the generated SSDT in the 'patched' folder but when searching for XCPM in Console nothing shows up - which I guess means it hasn't worked? Not sure if I'm missing a step somewhere. Was slightly confused as to what the Clover Configurator ACPI settings should be as the screenshots in the guide seem to be from an older version.

Anyway, it seems to be running OK now with the NullCPUPowerManagement.kext so maybe thats good enough..

 

[ammulder]

Thanks - I had a go at generating a SDDT for my CPU but it didn't seem to work - I ran the script, and placed the generated SSDT in the 'patched' folder but when searching for XCPM in Console nothing shows up - which I guess means it hasn't worked? Not sure if I'm missing a step somewhere. Was slightly confused as to what the Clover Configurator ACPI settings should be as the screenshots in the guide seem to be from an older version.

Anyway, it seems to be running OK now with the NullCPUPowerManagement.kext so maybe thats good enough..

You can try booting without NullCPUPowerManagement.kext and monitoring CPU speed via Intel Power Gadget and if you can boot and the speed shown in Power Gadget looks reasonable and your machine doesn't crash, then you're good. If that goes wrong, then perhaps the SSDT isn't right. You should have copied only SSDT.aml from Library/ssdtPRGen/ to EFI/CLOVER/ACPI/patched/ . If you need to, you can boot with cpus=1 again and put NullCPUPowerManagement back in.