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captaintrav
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CPU power management on Windows 10

Wed May 22, 2019 8:58 am

Stumbled across this lately that there are at least some cases where the power plan settings on Windows 10 is making BIG differences in performance. I'm not sure how turbo boost and everything plays with these settings but I'm talking about the "Processor power management" settings. The default is Balanced, minimum processor state is 5%. Change the power plan to high performance where this minimum setting is 100% and in some workloads, seeing a massive difference. Tested the same hardware in one case on Windows 7 and this was not the case.

I thought this was mostly a solved problem, but maybe there is some sort of regression or Windows 10 being too aggressive in trying to save energy? (This is not on battery power mind you).
 
meerkt
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Re: CPU power management on Windows 10

Fri May 24, 2019 4:59 pm

Random AMD data for Ryzen shows up to +8% FPS in High Performance vs Balanced:
https://community.amd.com/community/gam ... y-update-3
 
LostCat
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Re: CPU power management on Windows 10

Fri May 24, 2019 8:00 pm

meerkt wrote:
Random AMD data for Ryzen shows up to +8% FPS in High Performance vs Balanced:
https://community.amd.com/community/gam ... y-update-3

That was in 2017...potentially very out of date info there.
Meow.
 
synthtel2
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Re: CPU power management on Windows 10

Fri May 24, 2019 9:40 pm

That or something like it definitely still applies to my R7 1700. If Windows is configured to ever let it drop to its minimum state, it gets intermittently slower even when it should be maxed out (full load and anything reading frequency directly shows max).

Captaintrav, what's your CPU?
 
captaintrav
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Re: CPU power management on Windows 10

Mon May 27, 2019 8:43 am

synthtel2 wrote:
That or something like it definitely still applies to my R7 1700. If Windows is configured to ever let it drop to its minimum state, it gets intermittently slower even when it should be maxed out (full load and anything reading frequency directly shows max).

Captaintrav, what's your CPU?


My observations are on Skylake and Kaby Lake R laptops. I had heard a little about Ryzen parts, but this is new to me. What's more is we're not talking about a 8% difference, more like %50 difference in one case, and in a situation where you'd think the system would be more I/o bound - applying a Windows image from a .wim file. Although I am seeing smaller, but still significant differences in other apps. One situation was that users are complaining certain CPU intensive tasks were slower once they got Windows 10, when the hardware was either the same or faster. The weird thing is the CPU is clocking up to 3.6Ghz or so, just like it should (single threaded workload). Really puzzling why the power settings would have that much effect.
 
synthtel2
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Re: CPU power management on Windows 10

Tue May 28, 2019 12:27 am

That's a much bigger effect size than I ever saw.

Are you sure the minimum processor state is the key variable? If you boost that on the balanced plan, do things start behaving right?

If it is minimum processor state, can you test on a math-heavy workload versus an uncore/memory-heavy workload? AIDA64 has a good selection of both (probably something FPU and memory latency, respectively). If the uncore isn't clocking all the way up correctly, that should catch it (math-heavy should be unaffected, memory-heavy should see the slowdown).
 
johnbee
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Re: CPU power management on Windows 10

Fri May 31, 2019 12:57 am

synthtel2 wrote:
That's a much bigger effect size than I ever saw.

Only bigger, not the biggest.

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