MacBook Pro charging slowness under Mavericks NOT caused by smcFanControl (Updated)

MacBook Pro charging slowness under Mavericks NOT caused by smcFanControl (Updated)

[lead dropcap=”yes”]Update, March 18, 2014: It turns out smcFanControl was not the source of the problem. Or at least not the sole source. Within days of disabling smcFanControl, I was right back where I was before: Every time the computer needed to recharge, the kernel_task process would eat up all the CPU cycles and the MacBook would slow to a dead crawl. Back to square one.[/lead]

After a lot more digging, I think I’ve hit on the true solution in a post in the Apple Discussions Forum. This fix was not for the faint of heart because it involved editing a kernel extension in the root-level System folder, specifically IOPlatformPluginFamily.kext, removing a reference to my exact model of MacBook Pro. Apparently, there’s a bug in the process that tries to control cooling of the CPU. The setting is set by a reference to each particular model of Mac and by removing the reference it defaults to it ends up not doing anything, which in this case is better than what it was doing. The explanation is here if you care to read it.

Now my fingers are crossed that this is really the cure. At least until the next system update at which time let’s hope they’ve fixed the bug.

(Original Post) I’ve had a lot of trouble for months with my MacBook Pro with charging the battery, basically since upgrading to OS X 10.9 Mavericks. Every time I’d plug it back in after using the battery, the machine would bog down and become so slow until it was charged again.

Looking at the Activity Monitor, I could see a process called kernel_task using 800% of the CPU (meaning that it was taking up all of the capacity of the 8-cores of the CPU). I tried looking online for answers, only to find plenty of other owners of the same vintage MacBook Pro having similar problems, but with few solid solutions.

Long story, short, I was talking to a friend today who is an Apple Genius and he mentioned that it might be the SMC (System Management Controller) chip on the logic board and I might need to have the whole logic board replaced. I didn’t like the sound of that but it gave me an idea.

I’d seen in my Console logs references to a piece of software called smcFanControl, whose purpose is to allow me to manually control the internal fan speed if I think the computer is too hot. Anyway, there must be a bug in the software and now that I’ve disabled the software the problem is gone.

This doesn’t mean that everybody having the same problem has this software as the root cause, but it’s probably related to the SMC controller chip. Hopefully most can fix it with software like I did, but if not, then maybe a logic board replacement is in order.

Image Credit

  • MacBook_Pro: Own photo
Written by
Domenico Bettinelli