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From what I have seen on Youtube videos and from what I have read on the Internet, the undervolt value of the CPU core and CPU cache should be the same.

My CPU is i7-11800h. After running several tests, the stable undervolt value of the CPU core was -100mV; as for the CPU cache, it was -45mV. As you can see, the difference between the core and the cache undervolts is huge.

Is it ok to use those values? How would it affect performance?

If it is not recommended to use those values, is there an acceptable range for the gap between the CPU core and cache undervolt values?

machine_1
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2 Answers2

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It all depends on your CPU. Not the model, but the particular piece you got. Not all CPUs are made equal - some are more flexible when it comes to voltages, other not so much. This is not by design, but due to tiniest variantions in the manufacturing process. The common name for this is "silicon lottery".

The default values have to be quite conservative to work on majority of manufactured products. This means that unless you've had particularly bad luck, there's some room for undervolting. But how much will depend on how lucky you got.

The best way to assess the effect on performance is to measure it. There are too many variables: cooling efficiency, power stability and the luck factor too. Your setup is unique and only your own benchmarking will give you accurate results.

gronostaj
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You may reduce the temperature of the CPU in Windows by :

  • Go to Power Options > Change plan settings > Change advanced power settings > Processor power management > Maximum processor state
  • Set it to 95%
  • Reboot.

This will prevent Windows from using 100% of the CPU and reduce the maximum temperature, but you will hardly feel the 5% difference. If this is not enough, lower it some more.

harrymc
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  • Am not in the business of losing performance in competitive gaming so this doesn't work for me. Undervolting and slight underclocking is the way. – machine_1 Aug 22 '22 at 20:50
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    Even 2% will have an effect. Undervolting will also harm performance. – harrymc Aug 22 '22 at 21:00
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    @harrymc It's counter-intuitive but slight undervolting will most likely _improve_ performance: less voltage = less power = less heat = more turboing and less thermal throttling. It's possible because factory voltages are set conservatively to account for poor performers. – gronostaj Aug 23 '22 at 11:14
  • @gronostaj: In that logic, setting the CPU to 98% will have the same effect. – harrymc Aug 23 '22 at 11:15
  • @harrymc No, that way you're leaving 2% of the performance on the table. It could work to some extent with inadequate cooling solutions, but in a properly built PC you would be telling the CPU to never reach its full potential. The undervolting trick is different. The CPU starts off at 100% with max turbo (considering other factors) but will start to drop to lower turbo once it gets too hot to meet its TDP. Undervolting reduces heat emission and thus lets it maintain high turbo longer, and then drop to slightly higher turbo than it would otherwise. – gronostaj Aug 23 '22 at 11:56