What if I disable High Precision Event Timer?

Discussion in 'Motherboards' started by Anarchist420, Dec 12, 2012.

  1. Anarchist420

    Anarchist420 Diamond Member

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    What would happen if I disabled HPET?
     
  2. tweakboy

    tweakboy Diamond Member

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    Youd probably get a more stable and higher OC system. BTW that was a guess not the fact or opinion. What motherboard do you have Anarchist420 ? I would disable crappy things like that in the BIOS. gl
     
  3. Anarchist420

    Anarchist420 Diamond Member

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    Sabertooth P67 B3 by Asus.
     
  4. tweakboy

    tweakboy Diamond Member

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    I researched a bit and that settings will basically be blind. Meaning on or off there is no difference for your usage. People say disabling it gives them higher more stable OCes along with other options.


    Nice motherboard , Sabertooth pownz! military grade... fan on it 64GB RAM 9 3pin connectors...

    What CPU are you using with it and how much ram ?
     
  5. Anarchist420

    Anarchist420 Diamond Member

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  6. tweakboy

    tweakboy Diamond Member

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    Some report faster boot up times with it disabled. I recommend to disable it.
     
  7. ShadowVVL

    ShadowVVL Senior member

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    I was wondering the same thing about a year ago.never really understood what hpet did other then it was a cpu or I/O timer of some kind.

    I just left it alone.
     
  8. imagoon

    imagoon Diamond Member

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    HPET is mostly used for multimedia / syncing media streams with audio. If you disable it, the OS / app if it uses falls back to RTC and may start desyncing video. I can't really think of a good reason to disable it unless your systemboards implementation is crap (it happens). You also may need to force Windows (no idea on Linux) to only use HPET so the CPU isn't wasting time syncing all the rest of the system timers.

    bcdedit /set useplatformclock true (then reboot) enable HPET
    bcdedit /deletevalue useplatformclock (then reboot) disable HPET

    Mileage varies like all changes to computers.
     
  9. ShadowVVL

    ShadowVVL Senior member

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    Thank you imagoon for the explanation.hpet is no longer a mystery to me:)
     
  10. imagoon

    imagoon Diamond Member

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    HPET is a high resolution timer. RTC is normally around 3.4mhz where HPET is around 14mhz. The idea is that at say a 3ghz cpu speed, a lot can happen between clock ticks and it can be enough to start desyncing video / scientific work. Example:

    @3.0ghz -> about 882 cpu cycles occur between RTC ticks
    @3.0ghz -> about 215 cpu cycles occur between HPET ticks (also is typically 64bit counters)

    The main issue comes from how the timers are used. If they are sending interrupt based ticks, the CPU has to spend time handling those interrupts which happen more often in HPET so the balance is to increase timer resolution while not overloading the CPU with timer work.

    Add in that Windows 7 / Linux by default tries to manage all of the system timers and keep them synced, this can cause some CPU loading issues. Using the platform clock tends to clean this part up though because, in Windows at least, it makes windows only use HPET which can improve the system performance.