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  • Very periodic, very predictable, always the same, tested with portal 2, monaco, shadow puppeteer, hammerwatch.
  • Same regardless if I set the cpu at various min/max clock rates, always low cpu load e.g: 30% @90fps and 10% at 30fps.
  • Fresh win8.1 fujitsu siemens T904 with i7-4600U, disabled some crapware but pretty clean out of the box.

It leads to long mouse and keyboard input lag during low fps periods. Seemingly longer than the drop in framerate should warrant.

It's like the scheduler just pauses a lot during the lag period, and doesn't schedule anything much to run.

The machine is very cool, the fan doesn't even run unless I also start some browser tasks in the background.

I have no clue how to solve this. I can see the very nice periodic (and always quite low) cpu load over all 4 hw threads (dualcore * hyperthread).

Screenshots with portal 2 / shadow puppeteer running, fixed cpu clock speed (@75%/50%) (from power settings)

same with or without multithreaded rendering and various other graphics settings, and same in monaco and hammerwatch game as well.

Has anyone seen something like this before? I'm not used to Win8, or Windows at all for that matter. My google-fu is weak, obviously.

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This is related to intel speedstep/eist/c1e and how windows 8.1 misuses it.

I thought I should disable as many variables as possible, and went into the bios and disabled speedstep. The cpu locks to a fixed speed, and the periodic issues go away. Of course I can't keep it this way except for testing. Most of the time I use the laptop for regular work and not gaming, and I like some battery time.

FOLLOWUP QUESTION: does anyone know of any good custom thermal / speedstep/eist/c1e control software for windows 8.1?

However. I don't understand why it was behaving this way to begin with. I had the same issues regardless of which windows power management settings I used. The games don't use much cpu power and the cpu was idling most of the time. Exception was portal2 when running with vertical sync and fps cap off.

In power control options:
Tried "fixed" (same min/max) cpu speed. At various speeds ranging from 0.7GHz to 2.7GHz
Tried cooling policy passive / active.
Tried graphics performance max/min.

Same issues all the time regardless of power management settings. The laptop was always very cool, never got warm. Even when set to high "fixed" cpu speed and active cooling the fan almost never even turned on.

So, this brings me to the followup questions: How can I change the cpu/thermal regulation in win8.1? Any good custom control software out there? Or how to actually make the power control behave.

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    Welcome to the site and thank you for answering your own question. Maybe someone with a similar problem can find wisdom through your Q and A. Please do not include follow up questions in your answer. This is not a discussion forum where that is appropriate. Just ask a new question. However, questions asking for software recommendations are off-topic for this site. Mar 5, 2015 at 18:07

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