A1286 820-2915-B CPU throttling

[gurangax]

Re: A1286 820-2915-B CPU throttling

Excellent! Thanks for the update. Did you apply any special board straps after the GPU was removed?

sorry i dont get what you mean. i didnt put anything but just thermal pad for electrical insulation for the gpu heatsink, if thats what you meant.

[cruiser_]

Re: A1286 820-2915-B CPU throttling

Just have this problem today. throtled cpu. did you fix yours?

Nah, haven't got around to it again. My hope sits with nongen battery but that is a long shot
Do you have a genuine battery?
Is you GPU working fine? Mine is and I don't want to remove it just to prove the theory.
I can imagine it could pull SDA/CLK lines if it were shorted, that could cause throttling since no temp reading could be made

[gurangax]

Re: A1286 820-2915-B CPU throttling

Nah, haven't got around to it again. My hope sits with nongen battery but that is a long shot
Do you have a genuine battery?
Is you GPU working fine? Mine is and I don't want to remove it just to prove the theory.
I can imagine it could pull SDA/CLK lines if it were shorted, that could cause throttling since no temp reading could be made

Yup I have genuine original battery which comes with laptop. I bought this laptop for cheap from a guy who stored it after the screen went black. Turns out that it has been repaired before and I guess he doesnt want to repair it anymore probably because of high repair cost. The GPU was shorted before, it got too hot. So I removed the power coils for GPU core. that solve the problem which prevented the laptop to turn on. Soon (maybe a week later) it starts to throtle after using the cpu for high demanding app for long periods.

[cruiser_]

Re: A1286 820-2915-B CPU throttling

so i spent a few hours on this again today - down to looking at SMBUS communications between SMC and U55* chips with logic analyzer.
All looked fairly ok.
Was suspecting 'airport proximity' readings to be wrong but it was a dead end.

i am now chasing rabbit hole of not having reads on VN0R, TG1D & TW0P.

@gurangax can you please check if you are getting the values at all? Presumingly you are on MBP8,2/EMC2563?

[cruiser_]

Re: A1286 820-2915-B CPU throttling

Finally, SOLVED!!!

Put it on a shelf for some time and in the meantime I got my hands on a replacement A1382 battery made by 2power. Yes, a non-genuine Chinese knock off...

Lo and behold, no more throttling!!!

So new replacement A1382 battery from unknown manufacturer, even though correctly reported, charging up and in 'good' OS condition = throttling
Original battery from A1278 (same connector but different capacity) = throttling

Turns out that apart from GPU throttling issue which was the initial problem, the last piece of the puzzle was 'incompatible' battery. This is unbelievable. Gotta love Apple...

I wonder what they did exactly... blacklisted the serial?

'throttling' battery #1

Model Information:
 Serial Number:	W01484ND2D3BA
 Manufacturer:	SMP
 Device Name:	bq20z451
 Pack Lot Code:	0
 PCB Lot Code:	0
 Firmware Version:	201
 Hardware Revision:	000a
 Cell Revision:	158
 Charge Information:
 Charge Remaining (mAh):	6575
 Fully Charged:	No
 Charging:	Yes
 Full Charge Capacity (mAh):	6976
 Health Information:
 Cycle Count:	5
 Condition:	Normal
 Battery Installed:	Yes
 Amperage (mA):	577
 Voltage (mV):	12466

Original A1278 battery (throttling):

Model Information:
 Serial Number:	W053001C9D3BB
 Manufacturer:	SMP
 Device Name:	bq20z451
 Pack Lot Code:	0
 PCB Lot Code:	0
 Firmware Version:	201
 Hardware Revision:	000a
 Cell Revision:	158
 Charge Information:
 Charge Remaining (mAh):	4837
 Fully Charged:	Yes
 Charging:	No
 Full Charge Capacity (mAh):	4927
 Health Information:
 Cycle Count:	1805
 Condition:	Normal
 Battery Installed:	Yes
 Amperage (mA):	0
 Voltage (mV):	12441

2power battery (working fine!)

 Model Information:
 Serial Number:	C01514309YEF90MA4
 Manufacturer:	2-power
 Device Name:	A1382
 Pack Lot Code:	3230
 PCB Lot Code:	30db
 Firmware Version:	ddae
 Hardware Revision:	dac2
 Cell Revision:	2b39
 Charge Information:
 Charge Remaining (mAh):	7359
 Fully Charged:	Yes
 Charging:	No
 Full Charge Capacity (mAh):	7360
 Health Information:
 Cycle Count:	1
 Condition:	Normal
 Battery Installed:	Yes
 Amperage (mA):	0
 Voltage (mV):	12233

[gurangax]

Maybe its looking for battery full charge capacity of more than 7000mAh for it to enable full speed

[cruiser_]

Good spot and an interesting idea. I wouldn't be surprised if Apple actually implemented something like that