[SOLVED] CPU throttles during GPU stress test on laptop ?

[RedshiftVelocities]

Hello, I have an incredibly strange issue that I would like help in solving. My CPU throttles periodically and suddenly to 800MHz when I run a GPU stress test. However, stress-testing the CPU alone only results in a moderate reduction in clockspeed.

Laptop: Dell G5 5587 (i7 8750h, GTX 1060 Max-Q, 16GB of RAM)
GPU stress test: FurMark
CPU stress test: Prime95

Any advice you could give me would be much appreciated. I'm utterly baffled by this.

EDIT:
Here's some HWiNFO graphs giving more specific detail.

 

[rgd1101]

if you are doing gpu test, then it doesn't need to use the cpu much

 

[RedshiftVelocities]

if you are doing gpu test, then it doesn't need to use the cpu much

Yeah, except this symptom presents itself in games by my game running fine, then suddenly dropping to single-digit FPS for a few seconds, then returning to normal. Whenever this happens, the CPU has throttled to 800MHz.

 

[rgd1101]

plug in the power while playing?
sound like power throttling . could try https://www.techpowerup.com/download/techpowerup-throttlestop/

 

[RedshiftVelocities]

plug in the power while playing?
sound like power throttling . could try https://www.techpowerup.com/download/techpowerup-throttlestop/

It is plugged in. I've tried both XTU and Throttlestop at various points. Setting an undervolt helps a bit, but it doesn't fix the problem completely. Same with manually setting a lower power limit.

 

[uWebb429]

@RedshiftVelocities
Some Dell laptops are using an embedded controller (EC) to set turbo power limits for the CPU that are well below the advertised 45W TDP value. I have seen situations where the power limits get dropped to 5W or less. The result is massive CPU throttling down to 800 MHz. There is no fix for this common Dell laptop problem. The EC power limits are separate from the MSR and MMIO power limits that can be controlled by using ThrottleStop.

The other problem is BD PROCHOT throttling. This is also used by Dell to lock the CPU to 800 MHz. Dell started using some new throttling methods when they introduced their 8th Gen laptops. There are usually no simple fixes.

If you want more evidence of what is going on, turn on the Log File option in ThrottleStop and go play a game for 15 minutes. When done testing, exit ThrottleStop so it can finalize the log file. Copy and paste your log file data to www.pastebin.com and post a link here so I can have a look at it. Remember to exit HWiNFO while gathering data with ThrottleStop so the two programs do not interfere with each other. Post some screenshots of ThrottleStop so I can see how you have the program setup.

 

[RedshiftVelocities]

@RedshiftVelocities
Some Dell laptops are using an embedded controller (EC) to set turbo power limits for the CPU that are well below the advertised 45W TDP value. I have seen situations where the power limits get dropped to 5W or less. The result is massive CPU throttling down to 800 MHz. There is no fix for this common Dell laptop problem. The EC power limits are separate from the MSR and MMIO power limits that can be controlled by using ThrottleStop.

The other problem is BD PROCHOT throttling. This is also used by Dell to lock the CPU to 800 MHz. Dell started using some new throttling methods when they introduced their 8th Gen laptops. There are usually no simple fixes.

If you want more evidence of what is going on, turn on the Log File option in ThrottleStop and go play a game for 15 minutes. When done testing, exit ThrottleStop so it can finalize the log file. Copy and paste your log file data to www.pastebin.com and post a link here so I can have a look at it. Remember to exit HWiNFO while gathering data with ThrottleStop so the two programs do not interfere with each other. Post some screenshots of ThrottleStop so I can see how you have the program setup.

Ok. Will do when I get home. Thank you!

 

[RedshiftVelocities]

@RedshiftVelocities
Some Dell laptops are using an embedded controller (EC) to set turbo power limits for the CPU that are well below the advertised 45W TDP value. I have seen situations where the power limits get dropped to 5W or less. The result is massive CPU throttling down to 800 MHz. There is no fix for this common Dell laptop problem. The EC power limits are separate from the MSR and MMIO power limits that can be controlled by using ThrottleStop.

The other problem is BD PROCHOT throttling. This is also used by Dell to lock the CPU to 800 MHz. Dell started using some new throttling methods when they introduced their 8th Gen laptops. There are usually no simple fixes.

If you want more evidence of what is going on, turn on the Log File option in ThrottleStop and go play a game for 15 minutes. When done testing, exit ThrottleStop so it can finalize the log file. Copy and paste your log file data to www.pastebin.com and post a link here so I can have a look at it. Remember to exit HWiNFO while gathering data with ThrottleStop so the two programs do not interfere with each other. Post some screenshots of ThrottleStop so I can see how you have the program setup.

Alright, here's the info you requested. Something strange though: I needed to load my CPU a little bit (Prime95 test on 1 of my 6 total cores) to get it to throttle. I did previously restart my computer, so my assumption is that I had more background tasks running yesterday than I do now.

Log file: https://pastebin.com/3FbPZKND
ThrottleStop config:

 

[uWebb429]

@RedshiftVelocities
Your log file confirms the exact problem that I was talking about.

   DATE       TIME    MULTI   C0%   CKMOD  BAT_mW  TEMP    VID   POWER
2022-03-29  20:29:00   8.00   14.6  100.0       0   73   0.6625    6.4   PL1
2022-03-29  20:29:01   8.00   13.5  100.0       0   73   0.6643    6.5   PL1
2022-03-29  20:29:01   8.00   28.5  100.0       0   72   0.6617    7.6   PL1
2022-03-29  20:29:02   8.00   19.7  100.0       0   73   0.6559    7.5   PL1
2022-03-29  20:29:03   8.00   14.2  100.0       0   73   0.6564    6.7   PL1
2022-03-29  20:29:04   8.00   15.3  100.0       0   72   0.6605    6.6   PL1
2022-03-29  20:29:05   8.00   16.5  100.0       0   73   0.6575    6.5   PL1
2022-03-29  20:29:06   8.00   18.1  100.0       0   72   0.6592    6.9   PL1
2022-03-29  20:29:07   8.00   17.7  100.0       0   72   0.6600    6.6   PL1
2022-03-29  20:29:08   8.00    6.3  100.0       0   71   0.6631    6.7   PL1
2022-03-29  20:29:10   8.00    9.7  100.0       0   72   0.6617    7.2   PL1
2022-03-29  20:29:11   8.00   34.1  100.0       0   72   0.6633    7.9   PL1
2022-03-29  20:29:12   8.00   25.3  100.0       0   72   0.6600    7.7   PL1
2022-03-29  20:29:13   8.00   28.1  100.0       0   71   0.6642    7.3   PL1
2022-03-29  20:29:15   8.00    5.5  100.0       0   72   0.6600    6.4   PL1

8.00 in the Multi column shows that the CPU is being reduced to its minimum speed.

798 MHz (8.00 X 99.768 MHz)

The reason why this is happening is in the far right column. PL1 power limit throttling. If you look to the left of that column it shows that power consumption is mostly between 6W and 7W. You paid for a CPU with a 45W TDP rating. No laptop should ever be power limit throttling when power consumption is that low. The actual power limit must have been incorrectly set to 5W or less. The CPU is being forced to slow down as much as possible as it tries to get power consumption down to this incorrectly set limit.

ThrottleStop shows that the MSR and MMIO power limits are OK. That confirms that it is the EC feeding this low power limit to the CPU. The TEMP column while this is happening shows normal operating temperatures. There is no reason for this extreme amount of throttling.

Later in the log file shows TEMP warnings which means thermal throttling is in progress because the CPU is too hot. The heatsink needs to be cleaned and new thermal paste needs to be applied. If Dell sells a laptop with a 45W CPU, it should be able to run at the full 45W without thermal throttling and without power limit throttling down to 6W.

Contact Dell and ask for an explanation. This problem plagues a huge number of their laptops. As soon as I see a log file that looks like your log file, right away I know that this is a Dell laptop. Only Dell is using power limit throttling schemes that are this extreme.

 

[killian]

Have you using Dell Power Manager and setting to Ultra. This ups the fan speed to max. You can also do this with HWInfo - you can manualy set the fan speed to be maxed out.