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I have a Lenovo T480 with an Intel i7-8650U, which has the notorious problem of dropping itself down to 400 MHz whenever it feels like it, due to power limits. For example, even opening an application that uses the Nvidia GPU (before it even fully loads) causes the machine to throttle down and the fan to slow or stop. Intel Extreme Tuning Utility shows power limiting. Adjusting the power limits lower in XTU doesn't actually help anything. Neither does limiting the CPU usage to as low as 25% in the Windows Power Settings. (The CPU never goes above 25%, but it still clocks way up to 3.8 GHz.) I have outright disabled using the Nvidia GPU and instead stick to the Intel graphics, which helps but doesn't totally resolve the problem. This is a system power limit of some kind.

Naturally, I'd rather use my computer at a slower speed for longer, than suddenly landing at 400 MHz. It takes minutes for the Windows start menu to appear when I'm throttled at 400 MHz.

While I can't disable TurboBoost with XTU, I found that I could disable it with ThrottleStop. With TurboBoost disabled, my CPU never goes above 1.9 GHz. It also never goes lower. No power throttling! I can use my computer all day.

The down side of this is that when I'm doing normal things with spikey loads like web browsing, it would be nice if I could let that CPU go a bit faster. It doesn't need to go all the way to 3.8 GHz though.

Is there any way to limit the CPU clock speed while in TurboBoost?

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  • Can you post a picture of your Throttlestop setup. Did you try adjusting turbo ratio limit in throttlestop FIVR window?
    – lx07
    Dec 27, 2019 at 22:17
  • @lx07 Hey thanks for the tip! I hadn't messed with those as I wasn't sure what the numbers meant. I see now that they're multipliers. Cranking those down does indeed lower the clock rate and power consumption. If you could post that as an answer, I'd happily accept it. Thank you!
    – Brad
    Dec 28, 2019 at 0:29

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If you look in the FIVRoption of Throttlestop there is a section to alter the Turbo Boost multiplier limit.

FIVR

If you reduce the multipliers as far as they will go this will disable Turbo Boost while setting numbers between minimum and maximum will reduce the maximum Turbo Boost and thus heat. You would need to experiment to find suitable values.

As running 4 cores concurrently (which your CPU has) creates more heat than one or two you should consider making the multiplier higher for 1 and 2 than 3 or 4. Changing the turbo limit doesn't affect stability.

You can also consider under-volting to save more energy and this heat. This is in the middle of the FIVR screen.

You should change "CPU Core", "CPU cache" and "Intel GPU" to the same offset voltage (for example -100mV each) and test if it is stable both at high CPU use and idle. If set to high you will get a freeze or BSOD in which case power off and try a bit lower (for example -90mv). If it is OK you can increate the under-volt to -110mv and so on until you find a suitable figure for your particular chip. All CPU under-volt differently so you will need to experiment.

As a starting point you could take the figures found in this Lenovo forums thread: T480 throttling and high CPU temps

Undervolting was set to -100mV for the Core, the Cache, and the integrated GPU. The turbo ratio ratio limits were changed from 42/42/39/39 to 40/35/30/25 for 1/2/3/4 cores.

With these settings, the CPU stays at around 68 degrees celsius under moderate game load.

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  • Thanks for this detailed information! Very helpful. In my case, heat isn't actually an issue. Very rarely does the laptop get to the point where it needs to thermal throttle. My problem is power limits, before it gets hot. "EDP OTHER" on RING with PL1 on CORE. Setting things up to like 2.2 GHz actually keeps the power limit from happening, allowing the CPU to get to like 50-60C. Very rarely does it go above 70. Setting the multiplier to allow higher clock rates causes me to run into power limits very quickly. I've tried the undervolting thing in XTU, but missed the cache/GPU setting!
    – Brad
    Dec 28, 2019 at 16:23
  • @brad - I forgot to mention - don't ever try to use Throttlestop and XTU at the same time. Pick one or the other (I'd go for Throttlestop). Running both will lead to utter confusion and failure ;-)
    – lx07
    Dec 28, 2019 at 18:10
  • Thanks for the advice. I haven't changed any settings in XTU... only using it for its helpful graphs. Do you think that's an issue as well? (If so, I imagine I should totally kill off the XTU service as well, since that's running in the background, I've noticed...)
    – Brad
    Dec 28, 2019 at 18:12
  • As long as you only have one program trying to change stuff it should be OK. I think that is what the developer of Throttlestop (@unclewebb) says on the Throttlestop forums (I'm assuming the user-name here is the same person but perhaps not).
    – lx07
    Dec 28, 2019 at 18:17
  • Hi. I also used it today and fixed my laptop's heating performance and now gives consistent performance in gaming. Is it safe though? I didn't change too many settings. I just reduced multipliers for the four cores of my laptop. Nothing else.
    – Vikas
    Dec 15, 2022 at 8:51

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