Processor being throttled? - a workaround found

wimorrison · Mar 5, 2023

I have a Dell 7490 laptop with an Intel Core i5-8350U and 16Gb RAM that runs very well when first booted producing as Userbenchmark Desktop performance of 70% shortly after a cold start and allowing for all drivers to be loaded. This benchmark then drops to 15-20% after about 20 mins of use and it is down to the processor performance.

I have identified that immediately after cold boot the processor in Task Manager peaks to around 3.5GHz and this will provide the 70% benchmark. The processor drops to 0.40GHz at some point and sticks at that speed as shown below and it doesn't rise above this level. The processor temp shows at around 45-48C using HWInfo. Even starting Photoshop will not kick the processor above 0.40Ghz.

I have disabled the Intel Virtualisation in the UEFI, and also C States because I find that booting with them enabled throttles the processor to 0.40GHz for boot. I am getting very frustrated with this because it is essentially making the laptop unusable - even just for web browsing

Does anyone have any ideas what might be causing this and how I could stop the processor being throttled?

SlicEnDicE · Mar 5, 2023

Sounds to me that you have some heavy power saving options enabled that locks the CPU to max 20-25% of base clock.

wimorrison · Mar 5, 2023

The Power Mode set to Best Performance, any suggestions where else it could be set to throttle it?

SlicEnDicE · Mar 5, 2023

Check the Power Config profile advanced settings. There you can adjust min/max cpu speed for both when plugged in and on battery power.

SlicEnDicE · Mar 5, 2023

It is also posdible that Intel Power Management engine is broken. Seems to be a common issue on Dells.

To fix this, it requres removal of CMOS and laptop battery to reset everything.

But first you should try other options.

wimorrison · Mar 5, 2023

SlicEnDicE said:
Check the Power Config profile advanced settings. There you can adjust min/max cpu speed for both when plugged in and on battery power.

I can't find any advanced settings - just 3 options for Best Power Efficiency, Balanced and Best Performance

SlicEnDicE · Mar 5, 2023

Control Panel -> All Control Panel Items -> Power Options -> Edit Plan Settings

Change advanced Power Settings ->

wimorrison · Mar 5, 2023

Thanks - keep forgetting about Control Panel!

I have changed this to 100% minimum when plugged in, however the speed and throttling remains as shown above. I guess the next thing will be to remove the batteries, though that isn't as easy as it could be on these - though bizarrely they CMOS is much easier to remove than main battery!

TairikuOkami · Mar 5, 2023

Try Bitsum. Real-time CPU Optimization and Automation - there are many hidden settings in Windows.

wimorrison · Mar 5, 2023

OK, been though all the suggestions here and none seemed to make a difference - however one thing does seem to make a difference.

I accidentally pully out the power connector and the speed leapt from 0.40GHz to 3.5GHz!!! I can sort of repeat this by spinning the connector around to a point where the speed will again drop to 0.4GHz and upon removal of the power it will again leap up in speed. I am using a Dell 90w power supply with the centre pole which came with the laptop - could this be the issue? There are no warnings when I start the laptop using this SMPS, not when I plug it in and it seems to be ok - excepting for this strange observation.

Could a power supply, which is still charging the laptop and with no warnings, cause this sort of issue?

EDIT

I have now tried another Dell power supply and it is more definitive, I plug it into the laptop and the speed drops to 0.4GHz and unplugging it allows the speed to leap up to whatever is being demanded for whatever is running.

Anyone have any ideas wat the issue could be?

bobkn · Mar 5, 2023

At a guess, your CPU may be heating up. Cooling can be an issue in laptops.

Try a CPU monitoring utility. Maybe Core Temp. (I don't use that. My desktops have Corsair's iCue software installed.)

That doesn't explain what's happening when you unplug the charger, though.

Ghot · Mar 5, 2023

wimorrison · Mar 5, 2023

bobkn said:
At a guess, your CPU may be heating up. Cooling can be an issue in laptops.

Try a CPU monitoring utility. Maybe Core Temp. (I don't use that. My desktops have Corsair's iCue software installed.)

That doesn't explain what's happening when you unplug the charger, though.

I don't think it is temperature because I measured it and posted the temp in the original question

... The processor temp shows at around 45-48C using HWInfo ...

I have now tried two chargers and in both cases the speed is throttled back after a period, and all i have to do to get the speed back is unplug the charger for an instant recovery which will remain for 10-20mins, and then throttle again.

bobkn · Mar 5, 2023

My apologies. I missed the HWINFO temperature report. 48C shouldn't cause throttling.

walleyewarrior · Mar 6, 2023

Hi bobkn
Power throttling is built into windows laptops and remains in effect regardless of power settings.
You can completely disable it globaly or by individual app using task manager, gpedit or a simple reg entry.
I tried out win 11 for a couple of months and didn't care for it so went back to 10 for now. Anyway, the link below should still apply.

How to manage Power Throttling on Windows 10

Power Throttling is a feature to improve battery life on Windows 10, but when it doesn't work as expected, you can use this guide to manage its settings.

www.windowscentral.com

wimorrison · Mar 6, 2023

Thank you for this link which looks interesting, however the issue I have is the exact opposite.

My issue occurs when I plug in a power supply, the processor is throttled to 0.4GHz for everything - unplug the power and everything is back to full speed.

I have used 3 different Dell power supplies and they all cause the same behaviour.

EDIT - I have applied the settings in the article using GPEdit and the laptop continues to exhibit the same behaviours

SlicEnDicE · Mar 6, 2023

This is definitely a Dell specific issue. I see similar reports all over the web. A few has been fixed with a Firmware/BIOS update.

walleyewarrior · Mar 6, 2023

Couldn't hurt to try. I use a dell inspiron with the latest bios update and don't have that issue

wimorrison · Mar 6, 2023

I wouldn't say this issue is Dell specific. There are reports all over the net with HP, Lenovo, Acer and some other makes I have never heard off all suffering from the same problem - though there doesn't seem to be anything prior to 2018, and a large number in the 21/22 period.

It would also appear that there is no definitive solution, or in most cases any solution at all.

I have found that disabling Intel Speed Step Technology within the UEFI has fixed the speed of the processor at 1.7GHz which is what Windows says the processor frequency is (despite the processor having 1.9GHz as the base speed. This makes the laptop a bit slower, but much faster when on power than being throttled at 0.4GHz.

It would therefore appear that disabling the Intel Speed Step Technology allows me mask the issue, if not cure it. If anyone has any more suggestions please let me know as I would like to have the peak performance back again.

Ghot · Mar 6, 2023

Might want to Google differently.
Use the word laptop instead of DELL, maybe. It might be an issue that affects more than just DELL laptops.
Windows and probably the BIOS have lots of "laptop" specific software, that may be the cause.

Something like... laptop CPU throttling - Windows 11

Back in 2021, Win 11 Insider had some issues with the L3 cache on the Ryzen CPUs. Whatever the cause,
it was fixed by an MS update. But it was hard to Google because it "only" affected the L3 cache of Ryzen CPUs.

Some things to check...

How to Enable or Disable Power Throttling in Windows 11/10

Power Throttling in Windows 11/10 ensures that work gets done efficiently with the minimal battery power usage. Learn how to turn it On or Off.

www.thewindowsclub.com

https://thegeekpage.com/fix-cpu-is-not-running-at-full-speed-in-windows-11-10/

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\intelppm
On the Right side, click: Start and set the value to "4"
This disables Intel Power Management.

Precision 5540, Windows 11 and CPU Throttling | DELL Technologies

I've been experiencing performance issues and noted in the Windows Task Manager Performance window that the CPU spends most of its time at 0.79 GHZ, even if CPU utilization is above 80%.. I've con...

www.dell.com

This little tool looks interesting...

ThrottleStop 9.7.3 Download

ThrottleStop is a small application designed to monitor for and correct the three main types of CPU throttling that are being used on many lapto

www.techpowerup.com

Processor being throttled? - a workaround found

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