Will the Catalina fan noise decrease over time?

[mortenjensen]

Hi all,
I've just upgrade a 2018 MBP i7 from Mojave to Catalina - and immediately upon restart, the fans started to speed up. From google search I can see that this is a known problem. I have tried to reset SMC and PRAM without succes.

My question: Will it go away over time? Has it something to do with indexing in the background?

I have discovered that I can keep the fan down by using Turbo Boost Switcher and the turn off "turbo boost" - but of course that is not ideal, and you constantly have to allow it to run by typing the password.

So, should I stick with Mojave for a MBP 2018 i7?

Thanks
Morten

 

[robvas]

What apps are using the most energy in activity monitor?

 

[scooterspud]

How long has it been since the upgrade? If it's just been a few days, it could still be indexing.

To check, do a Spotlight search on anything - when the result comes up, if it is still indexing you will be told so right underneath the search result.

 

[Donnation]

Catalina is terrible, but, your fans shouldn't constantly be running. I would do an SMC reset and see if that fixes the problem for you.

 

[throAU]

Yes it will drop off.

After an OS upgrade, spotlight re-indexes basically everything, photos likely re-indexes everything, etc.

Give it a few days.

 

[mortenjensen]

Thanks for the replies. According to my unscientific test (by trying out the same setup under Mojave and Catalina), I've discovered the following:
- the MBP obtains the same temperature using Mojave or Catalina for about the the same amount of load. If turbo boost is enabled, it runs around 60-70 degrees.
- BUT: Catalina treats this temperature vastly different, spinning up as way before Mojave.

This is shown by these two graphs from Turbo Boost Switcher:

Mojave: (a) the temperature is running between 70-80 in turbo-mode and 65-75 in non-TB. (b) BUT the fan is running basically with the same speed all along (1500 or so).

Catalina: (a) the temperature in non-TB is close to 60 and raises only to 75 in TB-mode, at no point higher than under Mojave - (b) BUT the fan is running at a completely different speed: from 2500-6000!

CONCLUSION: It seems that Apple changed their tolerance in regard to temperature forcing the fans to cool much more at similar temperatures in Catalina compared to Mojave.

I do for this reason not think it will go away over time. I did leave it for a day or so to index, but the fan noise remained. This is "politics". Perhaps there is a good reason for this change, but I am really curious to know, if someone else discovered the same change of behavior going from Mojave to Catalina.

Morten

 

[matram]

Intel CPU have been running hotter and hotter. i believe 2018 was a model that had problems with thermal throttling. Maybe Apple changed the fan curves in Catalina to adress the problem.

 

[throAU]

If you're only a few days in it is still too early to make conclusions IMHO. I'm not saying your thoughts aren't maybe legitimate, but there's a lot going on in the background on macOS fresh installs these days - and especially if you don't spend a lot of time on AC power it may take a number of days to settle.

My new MBA took several days to settle down, photoanalysisd for example was running heavily in the background for some time (as I had 60+ GB of photos on it) - no doubt doing things like facial recognition, picking out objects/things for searches across images, etc.

It would not surprise me if the fan profile wasn't the only thing apple changed, the CPU scheduler has had various tweaks to run things differently on vs. off battery, if there is thermal headroom available, etc. - so you're likely comparing apples to oranges even after the indexing processes are done.

If you don't spend a lot of time on AC, a lot of background processes that only run on AC may take several days to complete.

I suspect your "same temp, faster fan" is because the machine is still doing a lot and ramping the fan to keep the temp in check - but it is working harder.

But yes, also as above, CPUs from intel have been getting worse (well, essentially intel is pushing the same thing just working harder) IMHO since Skylake.

For what its worth, I barely hear my MBA 2020 fan any more (Catalina from factory) - unless it's working hard inside a VM or such. I also ran Catalina from day 1 on my 2015 MBP13, and didn't notice any long term fan problems with that either - after it had enough time to settle.