iMac 2011: Fans at Max Speed, CPU Throttled to 1.7 GHz

Question

iMac Intel 27" EMC 2429

모델 A1312 / Mid 2011 / 2.7 & 3.1 GHz Core i5 or 3.4 GHz Core i7 Processor, ID iMac12,2

20 질문 전체 보기 | 27 부품 둘러보기

GidroGen @gidrogen

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iMac 2011: Fans at Max Speed, CPU Throttled to 1.7 GHz

Hello everyone!

I'm experiencing a serious issue with my 2011 27" iMac and can't seem to find a solution. Here are the main problems:

- All fans are running at maximum speed.

- The CPU is throttled down to 1.7 GHz.

- The GPU is operating at only 20% of its capacity.

- After waking up from sleep mode, everything works normally for about 10 seconds, but then the problems return.

Here's what I've already tried:

- Replaced the CPU with an i7.

- Replaced the logic board.

- Installed new RAM.

- Upgraded the SSD (from a Samsung 840 EVO 500GB to a Samsung 870 EVO 1TB).

- Installed an OWC In-line Digital Thermal Sensor specifically for my model, but it didn't resolve the issue.

- Disconnected the central HDD fan because it was very loud; however, reconnecting it didn't change anything.

- Reinstalled macOS High Sierra.

- Reset NVRAM/PRAM and SMC multiple times.

- Checked all cables and connections; the LCD Proximity sensor appears to be in perfect condition, but temperatures for Hard Drive Proximity and LCD Proximity are not displayed.

I'm using Macs Fan Control, Intel Power Gadget, and iStat for monitoring temperatures, but nothing changes: the CPU remains at 1.7 GHz even under load, and the GPU runs at minimal capacity.

Has anyone encountered a similar issue or have any suggestions on what else I can try? I would really appreciate any advice or help! Thank you!

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@gidrogen just to clarify. Nothing changed after you replaced all of those parts? The symptoms are identical with the old parts and all those new parts?

oldturkey03 의 2024년 10월 1일

@nick hey Nick, you tend to be pretty good with Macs, do you have any ideas?

shingle 의 2024년 10월 2일

@oldturkey03 Unfortunately, nothing has changed after replacing all the components I mentioned.

GidroGen 의 2024년 10월 2일

Have you tried changing the fan speed manually in Macs Fan Control? That's how I got around the full blast on my 21", and I've had no problems.

Best Of the Worst iPods 의 2024년 10월 4일

@bestofthew52619 As I mentioned, I am using Macs Fan Control, but it only partially resolved the issue with the fans. The CPU and GPU continue to run at low speeds.

GidroGen 의 2024년 10월 4일

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Dan @danj

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I’ve often encountered damaged inductors around the fan cable connection near the heat sink

I'll need to dig into my stuff to find a better image and there values, here's the location of the inductors

They are very small! You'll need a good magnifier to inspect them.

As to why the problem is present on both boards, could you have damaged them on both?

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Have you encountered issues related to reduced CPU and GPU frequencies? I mean, have you observed a decrease in their performance?

GidroGen 의 2024년 10월 1일

@gidrogen - Yes! Diagnostics won’t show the issue. These are small SMD devices that if your not careful get damaged trying to disconnect the cable.

Dan 의 2024년 10월 1일

@danj So, are you suggesting that the issue might be with the fan cable? Am I mistaken? If that's the case, how does it relate to the low CPU and GPU frequencies?

GidroGen 의 2024년 10월 1일

@gidrogen - Not the fan cable those little things near the connector if I remember correctly marked L101 & L102. What happens is the pressure of the tool resting on them breaks them when you try to disconnect the cable.

Dan 의 2024년 10월 1일

I have disassembled my iMac but was unable to locate the L101 and L102 modules. I thoroughly inspected the motherboard, and it appears to be in perfect condition. Additionally, I tested a second motherboard that I suspected might be the issue. However, replacing the motherboard with a new one did not change anything, and both boards look flawless.

GidroGen 의 2024년 10월 2일

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@gidrogen just to clarify. Nothing changed after you replaced all of those parts? The symptoms are identical with the old parts and all those new parts? — oldturkey03
@nick hey Nick, you tend to be pretty good with Macs, do you have any ideas? — shingle
@oldturkey03 Unfortunately, nothing has changed after replacing all the components I mentioned. — GidroGen
Have you tried changing the fan speed manually in Macs Fan Control? That's how I got around the full blast on my 21", and I've had no problems. — Best Of the Worst iPods
@bestofthew52619 As I mentioned, I am using Macs Fan Control, but it only partially resolved the issue with the fans. The CPU and GPU continue to run at low speeds. — GidroGen
Have you encountered issues related to reduced CPU and GPU frequencies? I mean, have you observed a decrease in their performance? — GidroGen
@gidrogen - Yes! Diagnostics won’t show the issue. These are small SMD devices that if your not careful get damaged trying to disconnect the cable. — Dan
@danj So, are you suggesting that the issue might be with the fan cable? Am I mistaken? If that's the case, how does it relate to the low CPU and GPU frequencies? — GidroGen
@gidrogen - Not the fan cable those little things near the connector if I remember correctly marked L101 & L102. What happens is the pressure of the tool resting on them breaks them when you try to disconnect the cable. — Dan
I have disassembled my iMac but was unable to locate the L101 and L102 modules. I thoroughly inspected the motherboard, and it appears to be in perfect condition. Additionally, I tested a second motherboard that I suspected might be the issue. However, replacing the motherboard with a new one did not change anything, and both boards look flawless. — GidroGen

C.D. @skull39 평판: 234 5 1 · Answer 1 · 2024-10-01T10:49:19-07:00

C.D. @skull39

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The only thing I can reasonably assume is going on here is that the software itself is trying to underclock your CPU somehow, almost like they do with iPhones and intentionally degrading performance to keep the battery life somewhat consistent.

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I have reinstalled the system, replaced the motherboard and SSD, and set everything up from scratch, but the problem still persists. Therefore, no program that slows down the computer should be present since I set everything up from scratch, but I can't resolve the issue :(

GidroGen 의 2024년 10월 1일

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iMac Intel 27" EMC 2429

iMac 2011: Fans at Max Speed, CPU Throttled to 1.7 GHz

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Update (10/02/24)

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