Macbook Air CPU throttled, flatlined at .80 GHz???

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Level 1

23 points

Macbook Air CPU throttled, flatlined at .80 GHz???

I have a MacBook Air, 13" 2012 A1466, with an i7 2GHz processor, 8GB ram. The logic board was recently replaced and the new board is remarkably slower. After browsing this site I came across Intel Power Gadget, installed and ran it. The frequency lines do not move, and it lists .80GHz as the IA (speed). Temperatures are a constant between 58-60 even with no activity. Fan speed is at 2000 and doesn't go up or down regardless of use. I have no errors when running diagnostics.

Geekbench 3 scores are unreasonably low, I get between 650/700 on average.

I troubleshooted and searched for answers. I tried resetting the SMC, the NVRAM, then restoring from a Time Machine backup, then tried a fresh install, and finally swapped out the SSD for another just in case that was the problem.

OS X is up to date, EFI and SMC are up to date, battery is brand new (and I tried 2 others). Tried disconnecting everything internal, the keyboard, touchpad, Airport card, LCD cable, reseated everything, booting one at a time just in case something was broken.

I have absolutely no idea what would cause the CPU to be locked at 800MHz. It seems to be some sort of protective mode? I've seen a few other people with this problem on here, but none with a solution.

Can anyone help? I'm looking for the Apple person equivalent to the "Click and Clack, the Tappet Brothers"!

MacBook Air (13-inch Mid 2012), OS X El Capitan (10.11.6)

Posted on Jul 24, 2016 11:35 PM

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Answer 1

metroline Author

Level 1

23 points

Jul 25, 2016 12:03 AM in response to metroline

Screenshot below of Intel Power Gadget and the Activity Monitor. The CPU maxes out when doing practically anything (running Chrome, Photoshop, opening and closing apps). This computer was still lightning fast before the logic board was replaced. I feel like maybe it is stuck with SpeedStep on full?

Normally, when the battery gets below 5% the system slows down like this, now it is permanently slow.

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Answer 2

John Galt

Level 10

141,718 points

Jul 25, 2016 2:35 PM in response to metroline

What does About This Mac report regarding the CPU speed? The obvious question is whether the replacement logic board was correct for your model MBA, and what Apple or its authorized service facility had to say about your concern. I assume you contacted them...?

Although I tend to disregard clever third party tools, the Geekbench score you report is indeed low.

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Answer 3

metroline Author

Level 1

23 points

Aug 3, 2016 12:23 PM in response to John Galt

About This Mac correctly shows the model as MacBookAir5,2 with a 2.0GHz processor. The logic board itself doesn't seem to be the problem, I swapped it out for another identical one and it had the exact same problem. I also tried swapping out the I/O board did not result in any changes. I installed a fresh copy of OS X, and then swapped out the SSD to rule that out.

The Geekbench scores are nearly identical with and without they battery installed. Another user recommended having the battery replaced. Its currently at an authorized Apple dealer being diagnosed. I'm hoping the battery is just malfunctioning. It has an original OEM A1405 battery installed, it lasts a really long time and has low cycle count (under 100), but maybe its delivering an inconsistent voltage or is otherwise defective.

I'll report back once they give an update!

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Answer 4

metroline Author

Level 1

23 points

Aug 3, 2016 4:15 PM in response to metroline

I got my computer back. All they did were a series of software diagnostics and said there was nothing wrong with it. I explained that it can't even run ordinary apps without grinding to a halt, and said I couldn't even load a YouTube video because the CPU throttling, and he said "it must be your internet connection."

I have an appointment with a real Apple Store tomorrow (this was an Authorized Repair place).

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Answer 5

John Galt

Level 10

141,718 points

Aug 3, 2016 7:17 PM in response to metroline

metroline wrote:

... he said "it must be your internet connection."

Well, that was certainly a waste of your time. Hopefully the Apple Store will offer more competent assistance.

From the screenshot you posted kernel_task appears to be throttling the CPU, causing your Mac to perform at significantly reduced capacity. Lacking legitimate reasons for a "protective mode" as you wrote, there are several possible causes: a defective battery, defective voltage sensors or defective internal temperature sensors are a few of them.

Apple Hardware Test can usually identify failed components, but its use as an exhaustive diagnostic tool is limited. An Apple Store can perform more extensive tests. An AASP ought to have those same tools, but from what you described, the competence of the shop you visited was lacking.

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Answer 6

metroline Author

Level 1

23 points

Aug 5, 2016 12:11 PM in response to John Galt

I went to the Apple Store, they ran the same diagnostics test and it passed every category. The tech I spoke with was able to confirm that there was still something wrong with it based on how incredibly slow it was running. They highly recommended against having them install a new battery since she said it would cost too much and there was no guarantee it would work, and that it wouldn't be refundable if it didn't solve the problem.

Her guess was that it is logic board related. I mentioned I tried two different logic boards, and she said if they were from the same place, it is at least possible that they are from the same 'bad batch.' Based on the age (4+ years) and cost of repairs, and the fact that I want to upgrade in the fall, she suggested not spending any more money on it.

Ignoring this defeat, I (much more cheaply) ordered an original Apple OEM battery from Amazon. If THAT doesn't work, at least it can be returned, and then I'm putting the whole thing on eBay and working from my PC until the new MacBook Pro 2016 comes out!

I'll update again when the battery arrives in a few days.

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Answer 7

Nov 29, 2016 7:19 AM in response to metroline

Ah, you didn't give us an update! I'm wondering because I have the same problem as you (Early 2011 MacBook Pro 15", with replacement non-Apple battery). Even running linux, it's stuck at 800MHz. This shows that the throttling is OS-independent, so that there is no way to fix it unless you can mod the firmware. I don't want to take this into an Apple shop since I'm not giving them any more of my money. I just want to know if a replacement battery from another manufacturer MIGHT work.

Any news?

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