fan noise after upgrade to Big Sur

THANK YOU!!! My MacBook has been driving me crazy for weeks and your answer seems to have worked for me as well. I really appreciate it! I was about to buy a desktop computer or try to uninstall Big Sur thinking my less than a year old MacBook Pro couldn't handle it. Seriously, bless you!!

Having same problem with my Mac Pro 2014 post Big Sur upgrade. No process is taking CPU time, I am getting 80 to 90% idle status but still noice is so bad that I am not able to use my machine, its starts immediately I start the machine. I contacted apple service center and they say that parts for my machine is not available so they can't fix this issue, some time post SMC reset I see that fan noice completely stops but after few hrs its starts again.

Is it a hardware or OC upgrade issue that causing this? pls help with proper solution.

I've tried everything short of wiping out my machine reinstalling everything from scratch. The steps related to Google Chrome didn't help, neither did signing out then back in to iCloud, resetting the SMC, the NVRAM, running diagnostics, or starting in safe mode. Apple tech support suspects it's a hw issue, but the only issue I see is that upgrading to Catalina, then to Big Sur has completely killed my battery on my late 2013 MacBook Pro, and now that I've installed a new battery, I'm afraid it too will be rendered useless if this keeps up. Performance has degraded to the point that I can no longer use this machine... as I type this note, the text appears 1 to 2 seconds after I press the keys. Very disappointing to end up in this situation, especially since this machine still has many more useful years left.

So I also upgraded to Big Sur and noticed the same symptoms. If you read my previous comments, you'll see that I tried everything recommended in the discussion forums, in fact, after installing a new battery I finally broke down, wiped my computer and installed Catalina in the hope that my problem would go away, yet no such luck. I ended up going to the nearby Apple store and having one of their geniuses look at it, and I believe he may have identified the issue. Apparently, there is a sensor that is no longer sensing... the system goes into a protection mode to prevent overheating by running the fans and slowing down the CPU. In my case (late 2013 15" MBP), the sensor is supposedly embedded in the battery, but since I tried to replace the battery, it's anyone's guess if there's a sensor in my new battery. The technician further informed me that these batteries really weren't meant to be replaced, but rather, for $199, they replace the entire top plate which consists of the battery, keyboard, touch pad, and top plate. I also noticed that they run a different diagnostic (AHT) which is no longer available, so all I could see from my diagnostic was that there was a problem with the battery, the power management system, and the SMC. The offending sensor is part of the SMC... The part is on order, and it should take up to 48 hours turnaround, so I'll be updating this comment once I get the new battery from Apple. Hopefully this will help those of you who are struggling with this issue... You may want to check your battery's condition (Apple -> About This Mac -> System Report -> Power -> Cycle Count). If it's over 1000, you may be ready for a new battery -> save yourself the aggravation and have Apple replace it for you, or buy a new Mac. To run the diagnostic, Shut down, and hold the D button while powering back up, wait for the spinning globe to appear, then wait for the diagnostic messages to appear. Good luck!

Following up to my earlier comment, I took my computer in to Apple and had them replace the battery. Turns out there is a sensor in the battery that failed which caused the system to turn on the fans and slow the processor in Eder to prevent overheating. Using aftermarket batteries most likely won’t solve the problem. They not only replaced the battery, but they replaced the entire top plate including the keyboard and touchpad. My MacBook now runs like new again.

Been struggling to get the mac book to be useful after Big sur update - The machine runs super hot, fan is on full speed, and machine is super sluggish. I had no issues with Catalina. It is some change Apple did with Big sur which does not play well - and may be for a purpose ?

The same problem after upgrade to Big Sur. No apps are running and fan makes noise.

MacBook Air 2020 i3

• Malwarebytes

Thanks, that appears to have solved the issue, I uninstalled Malwarebytes and the fans slowed down to normal!!

Great stuff and many thanks for your assistance

B

Likely spotlight re-indexing. Can take a couple of days.

I have updated my MacBook Pro 13 inch (2016) about 30 minutes ago and the fan sound seems to be decreasing. It will hopefully disappear completely (soon).

Same here. The Activity Monitor indicates kernelmanagerd is using most of the CPU. The fans are full blast even when the computer is doing nothing at all

Facing the same problem. I thought it was likely spotlight re-indexing but its been taking more time than usual.

It seems some 3rd party apps that get into a lot of disk access and syncing can cause this if they're not suitably updated for big sur.

Same here.

Same here, Chrome Helper runs even if Chrome isn't.