Need help with undervolting my Thinkpad X1 Carbon gen 6 i7-8550u

[sephiroth96]

Hey guys. I just got a Thinkpad X1 Carbon gen 6 i7-8550u, 16GB RAM, 512 SSD, FHD display. I love everything about the device, except for its cooling system, regular spikes in heat and the cooling fan. So I turned to Throttlestop, and it's also my first experience with it. Here's my settings:

In short, I managed to go as far as -90mV for Core and Cache, as -100mV once gave a BSOD during the TS Bench. I didn't touch the Intel GPU, or the Turbo power limits just yet, as they are a bit over my head for now. My goal is to keep this laptop's fan noise minium during daily tasks like Chrome, YouTube, and sometimes Photoshop, and I found the current speed shift EPP off 110 works. Things are working fine, but I'm still looking forward to getting some more juice out of this i7, but any EPP below 100 gives me some random spikes in heat and fan noise, which is annoying. So I have some questions to ask:

1. Did I miss anything in the settings? I left the Turbo Power Limits and Intel GPU as they are, so I'm wondering if any of them would give any significant result in performance or cooling effect?
2. Let's say I'd like the EPP to be 84 like the Windows balance mode default, which has the performance I prefer, but failed because of the fan noise. What are your suggestions?
3. Does anyone have experience with this kind of CPU or Thinkpad X1 Carbon Gen 6? Should I go any further with undervolting?

Thank you all in advance!

 

[unclewebb]

Should I go any further with undervolting?

My daughter has a similar Lenovo laptop with an 8550U. Her laptop was only stable at an offset of about -75 mV. Your -90 mV setting might already be going a little too far. If you have any BSOD issues, try setting the core and cache offset undervolt to -80 mV.

The heatsink in her laptop looks like a paper thin slice of Swiss cheese. Instead of Lenovo including extra metal to dissipate heat, they did the opposite and drilled holes in it to reduce the amount of metal being used. I would not be surprised if your laptop uses the same heatsink and fan. Poor design. The result is that if you try to run an 8550U at its full rated speed, temperatures will reach the maximum. Loud fan noise and thermal throttling will be the result.

To better control the power limits, check the MMIO Lock box at the top right of the TPL window.

Below that, clear the Disable Controls check box. Now you can set the MSR PL1 and PL2 power limits to whatever you like. If you want less heat, reduce the turbo power limits. Your CPU is set to 25 and 44 for PL1 and PL2. Consider reducing PL1 to 20 and set PL2 to 25. Reduce the turbo time limit from 28 to 8 seconds. Check both Clamp boxes in the Power Limit Controls section. This will make sure your reduced power limits are enforced. The inadequate heatsink is not capable of letting the CPU run at max power for 28 seconds. That is why I recommend about 8 seconds.

Will these settings reduce maximum performance? Yes they will. They should also help reduce the amount of fan noise. Intel recommends that PL1 be set equal to the rated TDP which is only 15W for an 8550U. If you want to reduce performance further to control noise, keep lowering the turbo power limits.

I prefer to set IccMax for the core and the cache to the max, 255.75. This helps reduce some unnecessary EDP throttling.

If you want to try adjusting the Intel GPU voltage, you need to adjust both the Intel GPU and iGPU Unslice. Somewhere around -50 mV would be a good place to start testing. I never bother adjusting these so I have not done much testing to see if this is a good idea or not. Most people find that the core and the cache are the two most important voltages to adjust.

I recommend using the Balanced power plan. This allows Windows to automatically set EPP to 84. If you do this, you do not need to check the Speed Shift EPP box on the main screen of ThrottleStop. I think adjusting the turbo power limits is the best way to get the right balance between performance and heat that you are looking for.

 

[sephiroth96]

My daughter has a similar Lenovo laptop with an 8550U. Her laptop was only stable at an offset of about -75 mV. Your -90 mV setting might already be going a little too far. If you have any BSOD issues, try setting the core and cache offset undervolt to -80 mV.

The heatsink in her laptop looks like a paper thin slice of Swiss cheese. Instead of Lenovo including extra metal to dissipate heat, they did the opposite and drilled holes in it to reduce the amount of metal being used. I would not be surprised if your laptop uses the same heatsink and fan. Poor design. The result is that if you try to run an 8550U at its full rated speed, temperatures will reach the maximum. Loud fan noise and thermal throttling will be the result.

To better control the power limits, check the MMIO Lock box at the top right of the TPL window.

View attachment 325638

Below that, clear the Disable Controls check box. Now you can set the MSR PL1 and PL2 power limits to whatever you like. If you want less heat, reduce the turbo power limits. Your CPU is set to 25 and 44 for PL1 and PL2. Consider reducing PL1 to 20 and set PL2 to 25. Reduce the turbo time limit from 28 to 8 seconds. Check both Clamp boxes in the Power Limit Controls section. This will make sure your reduced power limits are enforced. The inadequate heatsink is not capable of letting the CPU run at max power for 28 seconds. That is why I recommend about 8 seconds.

Will these settings reduce maximum performance? Yes they will. They should also help reduce the amount of fan noise. Intel recommends that PL1 be set equal to the rated TDP which is only 15W for an 8550U. If you want to reduce performance further to control noise, keep lowering the turbo power limits.

I prefer to set IccMax for the core and the cache to the max, 255.75. This helps reduce some unnecessary EDP throttling.

If you want to try adjusting the Intel GPU voltage, you need to adjust both the Intel GPU and iGPU Unslice. Somewhere around -50 mV would be a good place to start testing. I never bother adjusting these so I have not done much testing to see if this is a good idea or not. Most people find that the core and the cache are the two most important voltages to adjust.

I recommend using the Balanced power plan. This allows Windows to automatically set EPP to 84. If you do this, you do not need to check the Speed Shift EPP box on the main screen of ThrottleStop. I think adjusting the turbo power limits is the best way to get the right balance between performance and heat that you are looking for.

I didn't expect such detailed instructions from you. I applied the changes as above, and the laptop is now quieter than my cat. I can't thank you enough!

I wonder what this checkbox in the Power limit control does, and do I need to check it?

I prefer to set IccMax for the core and the cache to the max, 255.75. This helps reduce some unnecessary EDP throttling.

I also set IccMax to the max, but should I do this for the battery profile as well?

Your -90 mV setting might already be going a little too far. If you have any BSOD issues, try setting the core and cache offset undervolt to -80 mV.

And yes you got me. I set up my Throttlestop on the 13th, and and got several BSOD since then. So upon your reply, I raised the voltage back to -80. Works for now. But I have these logs from the previous BSOD. They're either ntoskrnl.exe or PSHED.dll. The Windows memory diagnostic tool said there was a problem with my RAM, but I don't kind of trust the tool. Do you think my over-undervolting could be the probable cause for this?

Thank you, and have a great rest of your day!

 

[unclewebb]

I wonder what this checkbox in the Power limit control does, and do I need to check it?

Checking the Lock box will lock the MSR power limits so they cannot be changed by any other software. You need to restart your computer to unlock a register that you have locked. There is rarely a need to lock the MSR power limits so most users leave this unlocked. That makes it easier to make changes to the power limits without having to reboot.

I also set IccMax to the max, but should I do this for the battery profile as well?

I always set IccMax to the max to prevent any unnecessary throttling. I do not own a laptop so zero throttling is always my one and only goal.

I raised the voltage back to -80.

I think I settled on -70 mV for my daughter's laptop. You should never see a BSOD. If your computer crashes when undervolting, add some more voltage and see if that helps.

Random errors when undervolting too much are common. I use the 960M TS Bench test as a quick stability test when undervolting. There should never be a list of blue screens showing up in BlueScreenView.

 

[sephiroth96]

Checking the Lock box will lock the MSR power limits so they cannot be changed by any other software. You need to restart your computer to unlock a register that you have locked. There is rarely a need to lock the MSR power limits so most users leave this unlocked. That makes it easier to make changes to the power limits without having to reboot.


I always set IccMax to the max to prevent any unnecessary throttling. I do not own a laptop so zero throttling is always my one and only goal.


I think I settled on -70 mV for my daughter's laptop. You should never see a BSOD. If your computer crashes when undervolting, add some more voltage and see if that helps.

Random errors when undervolting too much are common. I use the 960M TS Bench test as a quick stability test when undervolting. There should never be a list of blue screens showing up in BlueScreenView.

Thank you!