CPU throttling statically at 0.8GHz

Question

CPU throttling statically at 0.8GHz

I have 2 Macbook Pro, both manufactured in 2011 Early, 13 inch and 15 inch.

CPU are i7-2635QM and i7-2620M

Both suffered from same issue: CPU was throttled at 0.8GHz, statically, as the below image above:

This should not be "dynamic speed" feature, because the frequency was LOCKED as a straight line. when I capture this screen shot, GeekBench was running, the Activity Manager showed an almost 100% CPU usage. A strange thing is, Activity Manager only show the usage, but not show the real-time frequency.

The GeekBench 4 score is around 900, GeekBench 5 score is around 165. Much below the reference score, which is around 3000 for Geekbench 4, and 900 for Geekbanch 5.

The test was performed right after OS install+patching to latest update, nothing else app installed, except Intel Power Gadget and Geekbench.

already tried but not working actions:

SMC reset
NVRAM reset
PRAM reset
Re-install MacOS(From 10.7 to latest 10.13 with latest update/patch)

I fully understand that these machine is OLD ENOUGH.

I just want to find out the root cause, why it is throttling? If I can rescue these machine, I can preventing make two piece of elec-junk, proud of saving the earth. I am sure Apple will be happy on supporting me doing this : )

Below is the output of "sysctl machdep". If any more log could help, please share the procedure:

there is one line which looks suspicious:

machdep.cpu.thermal.energy_policy: 0

but no reference to find out the meaning and possible impact -_-

Log of sysctl machdep

MacBook Pro

Posted on Nov 22, 2019 4:51 AM

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Answer 1

Nov 23, 2019 6:19 PM in response to WhyNotSurface

WhyNotSurface wrote:

AHT result:

Alert! Apple Hardware Test has detected an error:

4xxx/4/40000005 Battery

in "System Information" the battery Condition is "Normal"

While the battery condition in macOS is fairly accurate the Apple Diagnostics do perform a bit more thorough test which can detect internal battery issues. It is possible the battery is causing your power issues since other contributors on these forums mention the system gets it power through the battery even when the power adapter is connected. Regardless, more power may be going to attempt to charge the battery than is being supplied to the Logic Board and other systems. You could try disconnecting the battery to see if it improves the CPU frequency issues. Are you using the proper charger for your computer (especially for the 15" laptop)?

So, question narrowed to:

1: Why the Fan speed is limited to 2000 in auto mode?

Probably because the CPU is throttled and the CPU and other temps are not getting hot enough to trigger an increase in fan speed. Obviously the fans & sensors are functioning normally if the Apple Diagnostics did not detect an issue.

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Answer 2

Nov 23, 2019 4:18 PM in response to WhyNotSurface

The main causes for CPU frequency throttling is either overheating of the CPU or a system power issue which is not providing sufficient power to the Logic Board and CPU. You can use Macs Fan Control to check on CPU temps and fan speed. I haven't checked the temps on that system in ages so I cannot tell you what is considered normal. You can try running the Apple Hardware Test to check on the proper functioning of the sensors and cooling system, but some people are finding that the AHT no longer boots on older systems.

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Answer 3

Nov 23, 2019 8:33 PM in response to HWTech

I happen have 2 pieces of MBP 2011 Early, now I disconnect battery on both of them, and make a compare:

Test:              15-inch.               13-inch

Battery:	       Disconnected           Disconnected

AHT:               No trouble found       No trouble found

System
Information:       Battery 0%             Not installed

CPU_Speed_Limit:   35%                    100%

CPU Speed:         0.8GHz                 0.8GHz

Don't understand the root cause of these difference.

Is there any log we can check, e.g. which component decide to throttle the CPU frequency? what is the condition which could triggering the throttling? as you mentioned, power and thermal are 2 possible trigger, then we can follow these clue, check log one by one:

check the log of thermal sensors

check the log of power supply on logical board

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Answer 4

Nov 23, 2019 5:27 PM in response to HWTech

result from Mac Fan Control:

When configured as "Auto", the fan speed is constant at 2000 RPM. This is the usual situation: even running GeekBench, there is no fan noise.

When configured as "Manually", it can reach 6200 RPM, and the noise raised significantly.

AHT result:

Alert! Apple Hardware Test has detected an error:

4xxx/4/40000005 Battery

in "System Information" the battery Condition is "Normal"

Sometime a even worse situation happened: the CPU_Speed_Limit drop to 35, will caused "REQUIRED FREQUENCY" in Intel Power Gadget also drops.

"pmset -g therm" output:

Note: No thermal warning level has been recorded

Note: No performance warning level has been recorded

2019-11-24 08:45:22 +0800 CPU Power notify

CPU_Scheduler_Limit = 100

CPU_Available_CPUs = 8

CPU_Speed_Limit = 35

During the GeekBench, the temperature stay in normal range

So, question narrowed to:

1: Why the Fan speed is limited to 2000 in auto mode?

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CPU throttling statically at 0.8GHz

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