I have a headless Quad-Core Mac mini living in the storage cupboard and in the last week or so which possibly coincides with updating to El Capitan has began having the problem, 600% usage from boot.
I've read all the posts out there about how to fix this:
system_profiler -detailLevel mini | grep "Model Identifier:" | sed "s/^.*: //"
Eventually yields Macmini6,2 so I then:
ls /System/Library/Extensions/IOPlatformPluginFamily.kext/Contents/PlugIns/ACPI_SMC_PlatformPlugin.kext/Contents/Resources | grep "Macmini"
Which provides the following:
Meaning my model's property list file is not present and as such I can't proceed with what has been for most a highly successful fix by moving/deleting or create an in-place backup followed by a reboot.
It's exactly the same outcome with an identical model also running El Capitan that lives on a shelf on my TV stand in my living room which acts as one of my Plex clients whilst also hosting my Windows 10 development VM via Fusion 8. I'd be devastated if it started happening to that machine. The performance would be unbearable.
So without a property list file how do I move forward? Any help gratefully appreciated. The headless machine runs several web apps very smoothly and has done so since I bought it. No new apps have been installed that may cause this.