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Disable C-States on i7 for fps boost
#1
I wonder if someone could explain this phenomena to me. I´m running a i7 720qm. My game is a pal version of ffx.

Whenever i disable the C-States in my bios i get 10 additional frames at least in those scenes where i would have less then 50 frames otherwise.

This happens every single time i try switching on/off C-States with the same scene.
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#2
A bit on what C-States do...
  • C0 – Active: CPU is on. C0 is the operating state.
  • C1 – Auto Halt: core clock is off. C1 is a state where the processor is not executing instructions, but can return to an executing state essentially instantaneously. Some processors also support an Enhanced C1 state (C1E) for lower power consumption.
  • C2 – Stop Clock: core and bus clocks are off. C2 is a state where the processor maintains all software-visible state, but may take longer to wake up.
  • C3 – Deep Sleep: clock generator is off. C3 is a state where the processor does not need to keep its cache coherent, but maintains other states. Some processors have variations on the C3 state (Deep Sleep, Deeper Sleep, etc.) that differ in how long it takes to wake the processor.
  • C4 – Deeper Sleep: reduced VCC

Does any of this sound like it could reduce performance?
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#3
it doesnt sound to me like it could. I read a lot before i posted this here, that´s why i asked you.
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#4
That's the idle detection messing up then.
With a little luck you can make this better by setting your energy saving plan to full performance.
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#5
C-States are basically for saving on power consumption. That kind of territory consists of lower clockrates, clocks turning off, flushing the cache and such, in favor of using less power. As a CPU goes further into that territory, it inevitably can take longer for it to come back.
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#6
interesting, though i set the energy saving plan to full perfomance already. But maybe it isnt working as intended...
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#7
If you go into the advanced settings of the Power Plans (under CPU power management), you can see what it does, and that it has set the minimum to 100% CPU usage. Other plans (like Balanced) are allowing down to like 5%.

But, yeah, this isn't the only thing that can control your CPU. Even on High Performance, Intel's Speedstep has kept control of my actually clockrates.
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#8
It's a problem to be expected with those automated solutions for power saving, if they were perfect you probably wouldn't even have an option to disable them Tongue2
Core i5 3570k -- Geforce GTX 670  --  Windows 7 x64
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#9
If any one was perfect, they wouldn't need so many ways of doing it. XD
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#10
well, i guess it´s just a strange side effect. But i´m happy the way it makes things better for me - whatever reason this may be.
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