MacBook Pro 15/16" 2018/2019 Underclocking to 800Mhz/1Ghz (Going extremely slow)

[LAHegarty]

Hello, only a few days apart this week both of my MacBook Pros have started underclocking to 800mhz/1Ghz for no apparent reason.

Macbooks are:
MacBook Pro 16" i7 (2019)
MacBook Pro 15" i7 (2018)

Both were working for months before that with zero issues, now both within a few days of each other have started going slow, so slow they are unusable.

I have tried:

• SMC reset
• OS reinstall (Monterey & Sonoma)
• I have cleaned dust from the fans

Nothing I have tried has worked, the cpu speed within 5 to 10 minutes or less reverts back to 1Ghz/800mhz making the computers unusable.

I am monitoring the clock speed via an intel app called Intel Power Gadget.

You can see under the Frequency chat it slowly drifts down the 1Ghz, this happens regardless of what I'm doing.

I'm willing to try suggestions.

The odds of this happening to both at the same time surely, must be quite high?

 

[specialstyle]

I would run something like geekbench on it while it's plugged in and on a cool surface like a countertop and watch that tool and see what happens. It is normal for the clock speed to ramp down if the machine is idle, so it would be good to see what happens under load. Are the fans spinning fast at idle, do they spin up when running the test, does the case get hotter than usual during the test, etc would be good info for us ;-)

 

[LAHegarty]

It's now happening on my 3rd MacBook Pro, this is unbelievable.

Now doing the same on MacBook Pro 15" 2019 i9

 

[arcite]

Fan vents might be clogged.

 

[real_mon2]

What are the stats of your internal battery on each? # of charge cycles? Condition of the battery?

Are you using the official 96W power adapter to power the unit? If not, suggest to use a 100W adapter with a certified 100W type C power cable. On this combination will delivery the required higher power by the logic board. Anything less will throttle the speed.

Have you approached Apple for assistance? Maybe a software update fault?

 

[LAHegarty]

Yes, I'm using good power supplies. (Never goes below 100% as always plugged in)
Vents are clear, yes.

Solution:

1. Remove all Widgets from the side bar.

2. Set fan from 50-85 (Average core temp) in Macs Fan Control.

3. Turn off universal control. (I don't know why but this helped massively)

(Optional Extras)
4. Use Low Power Mode (Optional) Which turns off boost. (In Battery/Power Options)
5. At some point I will re-paste the cpu and gpu, which should be done at min every 3 years.

One of the macs is a home server running Plex, and a few other programs and low power mode seems to keep it from underclocking.

That seems to have helped a lot.