CPU usage at 90 percent...sometimes.
I have two Macbook Pros. Both are model A1286.
The older one is a 2.4 GHz Core i5 machine with 4 GB RAM. Mid or late 2010.
The newer one is a 2.2 GHz Core i7 machine with 8 GB RAM. Late 2011.
Both have fresh installs of High Sierra, installed just two days ago, 10.13.2
The older one HAS NO ISSUES. It has a few music related apps installed on it and is trouble free.
The newer one has had nothing installed on it beyond the OS, plus Firefox. Firefox is also in the older unit. (Same version.)
The problem that I am encountering only affects the NEWER machine.
There are times when CPU load graph jumps to within a few points of 90 percent and I'm not even using Firefox at the time. Nor am I doing anything that would explain why CPU usage goes that high.
I may have NO apps opened when this occurs. The machine is quite sluggish in this state.
I've opened up the activity monitor to see what's going on.
When this happens, the kernel process shows activity up to around 800 or so? How can it be using 800 percent?
If at this point I close the lid and wait several seconds then open the computer back up, the CPU load graph now shows that load is normal, at or below 10 percent or so.
Second scenario: Open Firefox, go to YouTube, pick a video and start to play it. Activity monitor is open to watch what happens.
At some random point, CPU usage will again spike to around 90 percent and stay there. Kernel Task shows around 700 to 800 percent.
The process Firefox CP Web Content can sometimes exceed 100 percent but not for very long and that by itself does not cause CPU loading to spike.
If not using Firefox, and using Safari instead and viewing a youtube video from it, there is also a chance that Kernel Task will go ballistic.
What this is showing to me is that whatever is causing the kernel task to skyrocket and cause a 90 percent CPU load, it's not intrinsically linked to Firefox, or to Safari. It also happened even before I installed Firefox but I didn't at the time use the activity monitor to see why my mouse cursor was acting sluggish.
Again, the older 2.4 GHz i5 machine never demonstrates this problem.
The newer one has passed all diagnostics but the problem comes and goes.
There is only ONE thing that's "off" about the machine showing the problem, and that it is that it has a low cost aftermarket battery in it which diagnostics doesn't see. Diagnostics shows no battery. But the computer does recognize the battery and shows its charge state.
I DOUBT that a cheap battery can cause Kernel Task to randomly jump into the 800 percent range and 90 percent CPU loading.
Got any ideas?
Remember: When this CPU loading issue happens, I can ALWAYS stop it by closing the display/lid assembly, waiting a few seconds, and re-opening it and resuming operation. It always drops CPU load back to normal when I do that. I think that's critical information but I don't know exactly what is going on.
MacBook Pro, iOS 11.2.1, 2.2 GHz Core i7 8 GB RAM
