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I am using XPS 15 9550 with an i7 6700HQ processor. All below description is based on only using battery as power supply.

I created two power plans, one based on "High Performance" plan and another based on "Balanced" plan. Then I changed all power options of the new balanced plan to make it the SAME as the new high-perf one.

However, I can tell significant performance difference when using these two new plans (using battery only, without power plug). I checked the CPU frequency, and found that when using the one based on Balanced plan, the CPU uses very low frequency.

As far as I know, the only difference of these two new plans is their names (as I have changed them to make them identical in power option settings).

But why do they give difference CPU performance?

Below are the settings I used for both new plans.

Power plan settings

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First of all you assume that everything what changes with a different profile also has an option. That is not guranteed. We don't know.

Besides that, minimum processor state is 5% on battery. That leaves space for other programs to control the CPU frequency and behaviour. Windows doesn't control the CPU frequency all alone. Some programs can control their CPU demand, process priority and assignment to different cores by themselves. Usually there are even more options and tweaks in the BIOS/UEFI. Also be aware of preinstalled vendor software (e.g. Acer ePower Management) which can also control CPU usage.

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A) Why? What is the point in having a "balanced" plan, that isn't?

B) If you want identical plans with different names: Delete all plans and create new ones based on THE SAME base option.

C) Windows probably doesn't give you access to every option, and plans created as "balanced" probably have flags (in the registry, knowing windows) to scale the CPU, or limit it's voltage or frequency, or drop cores, or otherwise "balance" the power demands.

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As a partial answer: One of the differences seems to be that the powerplan templates change CPU settings, that aren't configurable in the interface.

More details are given in Hidden differences between system power plans in Windows?.

On my system, having all plans set to using "0-80%" of the maximum CPU freqeuncy the system in the "Power Saver" plan will cause the CPU to stay as close to the minimum frequency as possible (around 0.9 GHz), unless some task causes sustained high CPU utilization. As a result, this power plan feels unresponsive with noticable delays after keyboard input.

By contrast, a "balanced" plan causes the frequency to remain at the maximum according to the configuration (80% of 2.8 GHz base frequency, roughly 2.3 GHz) whenever as much as a browser is running, with ads constantly keeping the CPU at least somewhat active. It thus has good responsiveness but higher levels of fan noise and battery usage.

For demonstration:

Insights from QuickCPU

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