# Lenovo Legion Y545 Power Limit 4



## site (Mar 13, 2021)

Hello

First off, thank you so much for this program it's allowed me to get some amazing undervoltage with my CPU.

I'm posting because, although I was able to undervolt fine, I was running into a roadblock with my CPU not being able to actually hit its allowed Turbo Ratio Limits at "stock". No matter what I was adjusting with the voltage my laptop would never be able to go past 35 (~3541MHz), even though it's rated to hit 40 with all 6 cores active. Looking at the Limits tab it would always read red bar EDP Other under Core and RING when under load, and even sitting at idle it would yellow bar the same. Then I tried messing with Power Limit 4 under the TPL settings. The default was 60 and I, desperately trying everything, adjusted it upwards to an apparent sweet spot of 73, which suddenly bypassed the system's 45w PKG Power limit. I've successfully run Cinebench 20 and 23, as well as TSbench 1, 2, and 12 core on 120M and 960M, and have been playing Wolfenstein Youngblood for the last 3 hours and it has not dropped below 3990MHz while staying below 90C, with a PKG Limit of about 64w, and I have not seen a single EDP Other warning since changing it. This all is fantastic news to me with huge performance gains from stock while temps are lower.

The thing is, I don't actually know what Power Limit 4 is and what I'm doing by manipulating it, and I wanted to ask, before I set it and forget it, whether this is an ultra poweruser setting that I actually shouldn't be messing with unless I really know what I'm doing? Thanks


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## unclewebb (Mar 13, 2021)

Intel CPUs are designed to thermal throttle and slow down when they get too hot. Thermal throttling is important. If your CPU is hot, it should slow down to protect itself from damage. That is why ThrottleStop does not let you disable thermal throttling.

All of the other power limit throttling that Intel uses are not necessary. If increasing a power limit or turning a power limit off makes your computer run faster, that is great news. I usually set Power Limit 4 to 0. This is an easy way to disable this power limit on most computers. Either 0 or 1023 are good settings for Power Limit 4.


site said:


> set it and forget it


That is a good idea. Set Power Limit 4 so it never causes any throttling problems and then you can forget about it.

Also check the Disable and Lock Turbo Power Limits box in the FIVR window. This setting disables the secondary turbo power limits. They are not needed. One set of power limits is enough. You do not need 4 sets of power limits. Some of these limits are duplicated in multiple spots. That is crazy. Too many engineers at Intel were all designing power limits. They should have quit after designing one power limit but then they would have no job so every year they designed a new power limit. 

Check the Speed Shift box in the TPL window.

The 9750H is a locked processor so it cannot be overclocked. Using ThrottleStop enables your CPU to run at its rated speed. It is impossible to run a locked processor faster than its rated speed. That is what Intel likes to see. Intel also writes their own Extreme Tuning Utility (XTU) software for enthusiasts to use. They want enthusiasts to experiment with their Intel CPUs. No worries.

What are your voltage settings? The core and cache offset voltages do not have to be set equal to each other. Set the cache to -125 mV or slightly less and leave it there. Run a Cinebench R20 test with the core set to the same as the cache, -125 mV. Now start adjusting only the core in steps of -25 mV and run Cinebench again and again. You will probably get your best results with the core offset somewhere between -175 mV and -225 mV. Cinebench R20 is a great way to test different core and cache voltages. It is easy to see improvements with this test. When you find some voltages that you are happy with, run a couple of quick TS Bench tests just to make sure you are still stable. The Random option in the TS Bench test is useful too.


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## site (Mar 13, 2021)

Oh yeah way ahead of you there. That's why I was just curious about Power Limit 4, I had seen you talk here on the forums about PL0, PL1, and PL2, but not PL4.

Speed Shift - EPP is set to 80
Disable and Lock Turbo Power Limits is already checked

Core Voltage Offset I got down to -0.215, after that I ran tests all the way down to -0.250 and although it never crashed, there was no discernible difference in VID or temps
Core Cache Offset is at -0.140 because at -0.145 my system crashes, so I backed off by 0.005 for safety's sake

What's the difference between the Speed Shift - EPP setting in the main window and the Speed Shift box option in the TPL tab? Right now it looks like the defaults for the TPL tab option are unchecked Min 8, Max 45


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## unclewebb (Mar 13, 2021)

site said:


> not PL4


I just recently learned that this limit is called Power Limit 4 on the newer CPUs. The same register was originally called the PP0 Current Limit. When Intel switched to IccMax to control the current limit, they renamed this register to Power Limit 4. All I know is that if you set it to 0 or if you set it to 1023, it should not cause any throttling problems.

It sounds like you have already done your homework. No wonder your laptop is running so good.

The Speed Shift box in the TPL window controls the minimum and maximum CPU speed. I use this feature to easily adjust my CPU speed when I am doing some testing. It looks like your BIOS automatically enables Speed Shift. Checking this box helps ensure that Speed Shift will always be enabled and the Minimum and Maximum will always be set to what you want them set to. Your computer appears to be running great so no need to check this if it is not causing any problems.

Speed Shift EPP on the main screen lets you fine tune how Speed Shift works. An EPP setting of 0 is for maximum speed regardless of load, 80 is a good compromise and I never recommend going beyond 128. Maybe for a battery profile. When using Windows 10, checking the Speed Shift EPP box is usually not necessary. If you use the Windows Balanced power plan, you should have access to a power slider in the system tray. If you adjust that slider all the way to the right, Best Performance, Windows usually sets EPP to 84. When Speed Shift EPP is not checked in ThrottleStop. Move the Windows slider back and forth and watch the Speed Shift EPP value in the FIVR monitoring table. If Windows can control this, no need for ThrottleStop to control this too.


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## site (Mar 13, 2021)

It's interesting, with Balanced power plan on this machine it looks like the midway point is actually EPP 84 and Best Performance is EPP 0! So I've unchecked the TS SS-EPP option, set it to the midpoint on the Windows power taskbar icon slider (I ran c20 first to make sure that EPP 84 still hit 40x/3990MHz of course) to let Windows take care of it. It looks like everything is squared away and I'm ready to have all this set to go at boot. Thanks for the feedback, I appreciate it!


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