# Lenovo P52S, with i7-8650U, and eGPU. Windows 10.



## symb (Feb 6, 2022)

Hello, I've been reading this ThrottleStop forum here for quite a while and found lot's of useful stuff and good hints. However, I had to register and create a post about the strange behaviour that my CPU is giving me. 
I've been able to set the TDP limit (package power) to 25W from the normal 15W, but _on random soft restarts_ this changes even further, and I haven't been able to find out anything that causes this. 
"Normally" the behaviour goes something like, 10-15 seconds at 25W, and then drops to 15W. No heat issues or anything like that, it's just time related (probably turbo time limit). 
Ok, then sometimes the behaviour is similiar 25W top, except that the CPU _stays_ on 25W and doesn't drop back to 15W. No heat issues here either (because the eGPU in use, there's a lot more of cooling and power capacity only for the CPU).
And FINALLY, sometimes (last time today, like on my 3rd soft restart of windows), the max TDP/package power was 29W, and when running bench, the CPU sticked on the 29W no problem, no heat issues or anything.
I didn't change any settings between the restarts. I really like the latter case, because this keeps the cpu around 3.3-3.4GHz even under full load, and the performance boost is noticeable.

In addition to all of the above, I even had one restart (heh) where the CPU package was sucking around 30W solid, and stood there, unwavering.

So, is there a way I can make it to reboot on this, at least solid 25W state every time, or is this just some BUG randomly occurring on this particular Lenovo ?

Attached are the settings when this behaviour is happening. Also you can see the 29W max there, it's a fresh screenshot.

Thank's in advance for any clarifying explanation. Even if this can't be clarified.


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## unclewebb (Feb 6, 2022)

symb said:


> the max TDP/package power was 29W, and when running bench, the CPU sticked on the 29W no problem


What benchmark were you running? If you are running a benchmark that does not use the GPU, something like Cinebench, you will likely see a higher CPU power limit. If you have a Nvidia GPU that is active, your computer might reduce the CPU power limit so there is more power available for the GPU. 

There is a power limit managed internally by an embedded controller (EC) that ThrottleStop does not have access to. Ultimately, the 8650U has a 15W TDP rating so at any time, your CPU might be forced to run at 15W and there is nothing ThrottleStop can do about that. Your BIOS might not be eGPU aware so there could be some power limit bugs related to this. 





Your screenshot shows that Power Limit 4 is locked to 71. I am assuming that the BIOS has locked this setting. Entering a request value of 1023 is being ignored because of this lock. If Power Limit 4 is always locked to 71 after you boot up, you might as well enter 71.

I am not sure if your CPU uses the PP0 Power Limit. Try checking this box and change the value from 35 to 0. Reset the PP0 Turbo Time Limit to the minimum, 0.0010 seconds. This should tell the CPU to ignore this limit. 

Some laptops have bugs in their BIOS. The power limits might not be the same after first booting up compared to after doing a sleep resume cycle. Hold the Shift key down on the keyboard and then select Shut down or Restart in the the Windows menu. This tells Windows to do a full shut down and not a hybrid shut down. This might give you your best results or perhaps a sleep resume cycle will give the best results.


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## symb (Feb 6, 2022)

Thanks for the reply, unclewebb.
I've done some extended gaming sessions with doom eternal, for example, and the cpu stays on the 25W. It alway sticks with the 25W, 29W or whatever mode I'm randomly able to "boot" it to. 
So whenever this "bug" occurs, the result is pretty solid.

I'm going to play with the settings and reboots and see if I can come up with a conclusion how to reliably set the 25W or more - mode to the cpu.

One of the things that led to this +15W mode was disabling the Intel UHD and the discrete Nvidia quadro p500.
I am only using the external display attached to the eGPU, attached to the thunderbolt port.


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## symb (Mar 24, 2022)

@unclewebb 
Seems to be that this has already been covered here and there, but the behaviour is like following:
With eGPU attached to TB3 (Razor core in this case), the PKG power seems to be limited to 25W solid. Sometimes randomly, on some random soft reboots it goes to 29W.
Having a second PSU attached to the other USB-C slot doesn't have effect on this.

However, when you have any other docking station attached to the TB3 (I tried lenovo TB3 and some older DELL usb-c docking station), AND you attach a secondary PSU (Lenovo 65W for example) the PKG power goes to over 40W readings, and only limiting factor is the PROCHOT (I've set it to 95c so the laptop runs stable). Secondary psu off --> 25W, back on --> +40W. All on the fly.

There really is a difference when the CPU can go all in (in forms of bursts because limited cooling here) and keep all cores around 3800 for a moment and slowly coming down as necessary to keep the temps in limit.

Too bad it seems to be impossible to harness all this power (  ) with the eGPU attached. But at least this helps me to get the most out of this laptop as I use it to work mainly.


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## symb (May 12, 2022)

symb said:


> @unclewebb
> 
> ....
> However, when you have any other docking station attached to the TB3 (I tried lenovo TB3 and some older DELL usb-c docking station), AND you attach a secondary PSU (Lenovo 65W for example) the PKG power goes to over 40W readings, and only limiting factor is the PROCHOT (I've set it to 95c so the laptop runs stable). Secondary psu off --> 25W, back on --> +40W. All on the fly.
> ...


A little update:
I upgraded my work desktop with a usb-c display with LAN and enough usb ports, and daisychained the other display to it, so my old lenovo TB3 dock is now at home office.

And guess what, you can actually just plug the E-GPU to the TB3 port of the lenovo dock which is attached to the laptop via TB3, and as a result you get the CPU to harness all that sweet power to its benefit, as mentioned above.
So with lenovo TB3 dock and EGPU the 8650U now boosts 3,8-3,9GHz with PKG power around 43W, and only limiting factor is the CPU temperature. After the boost timer it falls back to 29W, which is 4W more than the normal 25W behaviour.

After accidentally noticing this first at work, it really made this laptop so much more of a workhorse even in a normal office environment.


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