Loud fan during screensaver

I've done some research into this issue and have found that the specific screensavers are the cause of this issue. I changed my screensaver to "Classic" using "Aerial" from the "Default Collection" and the issue has not happened since the change. I was originally using the "Flurry" screensaver which did cause the fan issue.

This leads me to believe that the issue is related to the specific screensaver itself and not something running in the background. I believe the new update has caused the specific screensavers that are causing this issue to render the graphics in a different method which is using the processor and/or graphics chip at a much higher level which causes the fan to kick in to cool the overloaded processor and/or graphics chip.

This is without a doubt a bug introduced by the 10.12.4 update and the obvious concern that I see with the introduction of this bug is that it will definitely effect the actual hardware of your device and lifespan of that hardware. I hope Apple sees this post and thread and looks into resolving this issue as soon as possible.

TLDR;

Change your screensaver... using the "Classic" screensaver with a photo set from the "Default Collection" will resolve this issue.

I have this same issue....just recently discovered two days ago. I spent the entire day on the phone with Apple Care...different times, each time the issue would return. Each tech specialist would attempt something new to fix the problem, the fan would seem like it wasn't going to run, then a few minutes after I would hang-up from them, walk away from my desk and return, the fan would be going crazy and draining my battery.

They showed me how to use the "activity monitor" and how to put it in my tray at the bottom of my desktop....this measures what programs on your computer are requiring the most CPUs, which in turn, requires the fan to run faster. Each time I would check it to see why my fan had started to run, the monitor would show that "nothing" was requiring a lot of CPUs. After the last Apple Care assistance at 5:30 last night, we thought it was fixed.

I went home, came back to work this morning...and the fan started again...draining my battery. I began to notice that each time it happened, I had walked away from my desk, and the screen saver had started. So, I took the screen saver off (chose NEVER in the drop-down), and it hasn't done it since.

I'm going to test it one more time...here in a bit....keeping fingers crossed this was the issue! If it works, my question is going to be "what" screen saver can we use that won't do this?

Arabesque and Word of the Day give me the problem, none of the others do. So just try some of the others to see what works best. I have had the same problem (MBA 2015) with Sierra and have updated to High Sierra and still have the problem.

Maybe this is hardware-related. If it was just a bug, Apple could have fixed this by now. And, since not every Macbook/MBA has this problem, hardware seems a probable solution.

CUP is running so high eating up all resources, heating up the unibody and running the fans so fast to try to keep the temperature low that battery is dying in about one hour when the screen saver is on.

...I miss Steve so much....

I'm having the same issue now after installing the update to 10.12.4 on a MBA 13" Early 2014.

It never occurred before this update and nothing else has changed other than installing the update.

For me, this is 100% related to the update being installed... Overall, this issue needs to be addressed.

My late 2013 MBP started with the same issue after updating to 10.12.4 - never happened before this. I have tried what others have done including several reboots etc. - Can't get rid of the fan spinning up during screen saver. This is obviously a bug.

Same problem here. Running on a MacBook Pro (Retina, 13-inch, Late 2013).

Proccesor: 2.8 GHz Intel Core i7

16 GB 1600 MHz DDR3

Screen Saver: Arabesque...

Never happened before 10.12.4.

Makes me think twice about Apple's quality nowadays...

+1 on this; 10.12.4 update; screensaver triggers CPU usage of some kind; can't view activity because the screensaver is on... nothing in logs indicating an issue. My guess is it's related to a process that only updates on idle like a backup program (ie iDrive) or Google Chrome updater (in my case anyway).

Fixed!

I had the same problem, it started a few weeks ago when I upgraded to 10.12.4 I'm on a 2015 MBP. Everytime I put the display to go to screen saver and go away from my desk, I'd come back maybe only minutes later, to hear the fan at full pelt! But as soon as I went back to doing something on the macbook, the fan returned to normal.
I'm quite tech savy, ran Apple diagnostics, cleared my memory, shut down programs etc, but nothing seemed to help until I read the replies here!

As stated in a previous reply by someone above, I changed my Screen saver from Arabeque to just Ken Burns, and it seems to have fixed the problem. I've been checking almost every hour, and the problem has not occured since!

This is really helpful. Thank you! I was getting super worried.

Just to note that I this issue plagued me with the 'Arabesque' screensaver. As of today's date (August 15th 2017) I am running macOS Sierra v10.12.6.

Come on, Apple! Fix the problem!

Open Activity Monitor to ALL PROCESSES and CPU and see if there is any process that may be responsible for the fan speeding up.

Also run an Apple Hardware Test:

https://support.apple.com/en-us/HT201257

Note that an error free AHT is not conclusive.

Ciao.

I have the same exact problem. Fan is at 100% when the screen saver is on. As soon as I wake the screen it dies down very soon after that...about a minute or less. I have searched many posts and posted this elsewhere. No response.

Also having the same problem - as soon as the screensaver comes on, the fan gets really noisy...also dies down when I click back on the screen. Resetting smc doesn't help. Is the screensaver really that intensive? Kinda defies the point of having one if so.

Same problem here. FYI: I'm using the screensaver Word of the Day.