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Thread: High Precision Event Timer

  1. #1
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    Exclamation High Precision Event Timer

    Can anyone explain to me what HPET does exactly?

    A guy on another forum claimed that by disabling it, his DPC latency plummeted and his gaming performance improved; most notably the microstuttering.

    So I tried it myself, and the difference to my astonishment, was very noticeable. First off, my DPC latency dropped big time. Not that it was high to begin with, but now it hovers below 10 for the most part.

    Second, I noticed that general windows performance felt snappier. I know I'm not imagining things, because like many, I scrutinize my system so I'm sensitive to even minute changes in performance.

    And last but not least, gaming performance is definitely smoother. Anyone with SLi will tell you that occassionally when playing a game, you experience a bit of lag or stuttering for no apparent reason whatsoever. Most people attribute these minor discrepancies to SLi, but what if it's something else?

    Because I can tell you, that my overall gaming experience has improved since turning HPET off
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    HPET is High Precision Event Timer. It's exactly that..
    It can be used by software or the os for very accurate timing, however when it's "ON/Enabled" then windows will use it as the main clock source instead of the other options like the cpu TSC (time stamp counter).

    The HPET can provide more precise timing, however the OS has to reference it via a memory address, or I think the HPET can raise a interrupt,
    so therefore it's slower.

    The TSC may be less precise, however it's a register in the CPU so this is the fastest possible way to access a clock source.
    Last edited by CrazyNutz; 10-19-2010 at 05:46 AM.
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  3. #3
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    Disabling it is a great tip. I couldn't figure out why my DPC latency was so high before. It shouldn't cause high latency, though... :\ Needs fixing by EVGA.
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    Carfax can you run some benches to see how much difference it makes? Say Vantage and 03?


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    very interesting, i would also be interested in seeing if it makes any difference to benchmarks.

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    Quote Originally Posted by CrazyNutz View Post
    HPET is High Precision Event Timer. It's exactly that..
    It can be used by software or the os for very accurate timing, however when it's "ON/Enabled" then windows will use it as the main clock source instead of the other options like the cpu TSC (time stamp counter).

    The HPET can provide more precise timing, however the OS has to reference it via a memory address, or I think the HPET can raise a interrupt,
    so therefore it's slower.

    The TSC may be less precise, however it's a register in the CPU so this is the fastest possible way to access a clock source.
    Great explanation dude, thanks If the TSC runs from the CPU register, then that could definitely explain the performance increase I'm seeing..

    BTW, I opened up a similar thread on Nvidia forums and some of the replies are interesting.

    Quote Originally Posted by zalbard View Post
    Disabling it is a great tip. I couldn't figure out why my DPC latency was so high before. It shouldn't cause high latency, though... :\ Needs fixing by EVGA.
    Do you have an Nvidia card? It's possible that Nvidia drivers may have issues with HPET.

    Quote Originally Posted by chuchnit View Post
    Carfax can you run some benches to see how much difference it makes? Say Vantage and 03?
    I'm waiting for my monitor to return from repair before I start running benchmarks. It's supposed to be here tomorrow, so if I have time, I'll run them then..

    I can run some Everest benchmarks to see if there are any differences in bandwidth and latency in the mean time however..
    Last edited by Carfax; 10-19-2010 at 08:40 AM.
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    Quote Originally Posted by Carfax View Post
    I'm waiting for my monitor to return from repair before I start running benchmarks. It's supposed to be here tomorrow, so if I have time, I'll run them then..
    Thanks I'm waiting on my CPU to get here or I would test myself.


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    I'll test tonight. This actually makes sense, but I need to see how high my DPC latency is in the first place.

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    Quote Originally Posted by Kain665 View Post
    I'll test tonight. This actually makes sense, but I need to see how high my DPC latency is in the first place.
    Use this tool to see what it is.
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  10. #10
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    Quote Originally Posted by carfax View Post
    do you have an nvidia card? It's possible that nvidia drivers may have issues with hpet.
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    Quote Originally Posted by jayhall0315 View Post
    If you are really extreme, you never let informed facts or the scientific method hold you back from your journey to the wrong answer.

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