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feature idea - per multiplier undervolt

henry432

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Jun 13, 2021
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Hello, while i was undervolting my laptops i7-9750hf, I have noticed the large frequencies (3ghz+) can take a higher undervolt than lower frequencies. but if i leave higher undervolt when it goes below 3ghz it crashes

so i would like to ask. Would it be possible to edit the voltage by a different margin for each frequency?
 

unclewebb

ThrottleStop & RealTemp Author
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Jun 1, 2008
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The 10th and 11th Gen desktop CPUs allow you to set up a voltage frequency table. I do not think this feature is available on the 9th Gen mobile CPUs.

Trying to manage the voltage by using software like ThrottleStop would cause a lot of overhead. The CPU multiplier and voltage can change hundreds of times per second. You would need to monitor the CPU for any changes more often than that and even then, there are going to be times when the voltage drops faster than ThrottleStop can respond so you will end up with a crash / BSOD.

when it goes below 3ghz it crashes
Set your CPU up so it always runs at maximum speed. Use the Windows High Performance power plan and make sure that this plan is setting Speed Shift EPP to 0. There is no need to run Intel CPUs slow when they are plugged in. As long as the low power C states are enabled, you can get really good power consumption even if the CPU is running at maximum speed when lightly loaded or idle.

 

henry432

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@unclewebb what about system agent undervolting? currently tested -100mV and its stable. does it help reducing the temps?

if i set speedshift epp to 0 it would run hot in cpu intensive tasks like games

also about the voltage/freq table
in hwinfo64
for cpu core/cache it shows voltage offset enabled, voltage override enabled
voltage offset is what throttlestop currently does i guess?
but what's voltage override? the voltage override is not enabled in system agent but i can still change the offset, set constant voltage value in throttlestop.
 
Last edited:

unclewebb

ThrottleStop & RealTemp Author
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what about system agent undervolting?
Most people do not bother adjusting this.

does it help reducing the temps?
Probably not that much or you would see more people undervolting this. If the System Agent does not consume a huge amount of power, reducing the voltage is not going to result in a huge savings in power. When my desktop CPU is loaded, the System Agent only consumes about 1% of what the cores consume. You are more likely to lose stability before you accomplish anything by undervolting the System Agent.

voltage offset is what ThrottleStop currently does I guess?

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The Adaptive option in ThrottleStop allows you to request an offset voltage. The Static option is used to request a fixed voltage. On my CPU, only Adaptive / Offset is available for the System Agent. The core and cache and Intel GPU allow both options. I do not have access to a wide variety of hardware so I do not know if the Static / Fixed voltage option works for every CPU or how it works on every laptop. It is possible that Static voltage requests will only work over a certain range like 0.6 V to 1.52 V or the requests entered in ThrottleStop might not work at all on some CPUs. When I am not 100% sure about what CPUs are supported, I try to leave options unlocked so users can experiment. Intel does not share their full documentation about the FIVR with individual developers like myself. This stuff is all a big secret at Intel. They probably cringe every time I figure out something new. :)

For most laptops, the Adaptive / Offset setting works best. This setting is used to lower the CPU voltage along the entire voltage curve. It does not allow one to perfectly match the voltage to the CPU speed from idle to full speed. Other than that, it works quite well to reduce laptop temps.
 
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