Sandy Bridge and stress testing with Linpack (Linx, IBT, OCCT)

Discussion in 'CPUs and Overclocking' started by Dufus, Jan 16, 2011.

  1. Dufus

    Dufus Senior member

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    Thought I'd share some test results of stress testing SB with Linpack to show the difference between running with the new AVX (256bit registers) and the older SSE (128bit registers). SSE results gave ~47GFlops @ 3.4GHz while AVX results gave ~83GFlops @ 3.4GHz.

    Stock CPU clocks, 33x multi with 34x 4 core turbo.
    Stock Vcore (Auto).
    Stock cooler.
    EIST disabled.
    C1E, C3, C6 disabled. This means higher idle temps/power but makes it easier to see what is happening with the loadline.

    The first run is using the standard SSE 128bit registers.
    [​IMG]
    Measured power into the VRM was ~89W


    The second run is using the AVX 256bit registers. I haven't heard if there's going to be support for use of the AVX registers in Windows versions earlier than W7 SP1.
    [​IMG]
    Measured power into the VRM was ~108W


    On the 4th run some turbo throttling can be seen, turbo shown as yellow. This seemed to happen a little before PROCHOT and TDP.

    Working with CPU temperature and VRM power seems to show an increase of ~20% in power usage over running SSE while the Intel energy register shows ~30%. Some further investigation is required for the discrepancy.


    Notes:
    Realcore EIST TM mode works a little like TMonitor. Core numbers are APIC numbers and may appear odd but there are only 4 cores. Time in seconds on the Y axis and multiplier/load on the x-axis. Sampling is 100x per second. Averaged multi shown under the core number is calculated over the first section which in this case is 0.0 to 1.0 seconds.

    Realcore PECI uses the PECI interface to report the hottest core with a 1/64th degree resolution.
     
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  3. MangoTBG

    MangoTBG Diamond Member

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    Thanks for this!

    I wanted to see how my Phenom x6 1055 @ 3.5GHz faired against these beasts. My results were 68.xx GFlops.
     
  4. Dufus

    Dufus Senior member

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    Your welcome, glad it was helpful.

    AFAIK Linpack is optimized for Intel processors so your 68.xx result might not be showing the full potential of your chip. I wonder what the results would be if AMD produced an AMD optimized benchmark to solve the same set of linear equations as Linpack.

    The main reason for posting this was to make people aware that stressing SB with AVX will use significantly more power. Once SP1 is released for W7 then we might see some posters needing to tame down their high clocks. Then again maybe they will feel it's not necessary because currently there is very little in the way of software that will stress the chip that high.

    Not sure how long it will be before good use of AVX is made in software. Maybe some number crunching software will incorporate AVX quite quickly but for normal users it might take some time before their use is seen, perhaps years.
     
  5. Dadofamunky

    Dadofamunky Platinum Member

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  6. reb0rn

    reb0rn Member

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    I had 5.2Ghz stable on air ~95C (no avx linx and prime) and now i can only manage ~4.8Ghz maybe 4.9 with win7 SP1 and avx linx .... the problem is temperature now at 5Ghz in 20 secands it hit 99C and start to trottle down
    also i had to bump voltage up 0.01v

    4.8Ghz gave me 122Gflops

    btw windows sp1 is RTM so its final :)
     
  7. Dufus

    Dufus Senior member

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    Thanks for the feedback reb0rn. AFAIK SP1 has not been made official yet although there seem to be leaked version(s) claiming to be RTM. Once MS releases SP1 officially we should see a lot more 3 figure Linpack benchmarks for OC'd SB users.
     
  8. neosapien

    neosapien Member

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    Where can I download this "realcore" program you're using? I tried googling, found nothing.
     
  9. smakme7757

    smakme7757 Golden Member

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    Where can i download Windows 7 SP1 so i can try as well?
     
  10. AdamK47

    AdamK47 Lifer

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    Is LinX specifically coded to use the AVX 256-bit registers then?
     
  11. Dufus

    Dufus Senior member

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    @neosapien Realcore isn't publicly available.

    @smakme7757 If you can not wait for the final release then the SP1 used above was a RC downloaded from Microsoft.

    @AdamK47 It is Linpack that is coded to use AVX, in particular ver 10.3. Linx, IBT and OCCT are front ends designed to make the running of Linpack a little easier to use via a GUI and help in reporting the results.

    Here's what Linpack looks like natively when run from the command line. (The actual CPU frequency was 3.4GHz)
    [​IMG]
     
  12. jones377

    jones377 Senior member

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    Dufus, that's a much better Linpack score. I was starting to worry about SB efficiency running AVX for a while there. Now at 87% of peak. I bet with further compiler optimizations it will go up a bit further.
     
  13. Dufus

    Dufus Senior member

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    The problem size / amount of memory makes a difference. Those first 2 only had 1GB.
     
  14. reb0rn

    reb0rn Member

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    Anyone has problem with linx with new linpak (avx+win 7 sp1) produce errors after 3-4h of a test?
    I just updated new bios on asus and even tested at stock speed but after 3h 12m i got this:
    18265 18280 4 41.861 97.0566 2.828071e-010 3.005782e-002
    18265 18280 4 41.705 97.4195 2.828071e-010 3.005782e-002
    18265 18280 4 41.801 97.1976 2.666694e-008 2.834264e+000

    Stooped upon error .. :(
     
  15. SickBeast

    SickBeast Lifer

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    What I do lately as a stability test is to run LinX, SuperPi (32m), and the Prime95 "blend test" simultaneously.
     
  16. reb0rn

    reb0rn Member

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    I agree,
    but so far i am not sure if linx + new linpak have a bug, atm runing intel burn test with new linpak to see if it gona reproduce error also...
     
  17. Bryf50

    Bryf50 Golden Member

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    Holy crap AVX takes a lot of power. I have my power draw set to 105W and it was still hitting the limit and downlocking. That said 100 GFlops is pretty cool.
    [​IMG]
     
    #16 Bryf50, Jan 22, 2011
    Last edited: Jan 22, 2011
  18. SickBeast

    SickBeast Lifer

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    Can you get your x6 any higher than that? I'm considering one for a future upgrade, but I'm hoping for 4.2ghz.
     
  19. Bryf50

    Bryf50 Golden Member

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    Also to anyone who wants to give avx a try skip the release candidate service pack 1 and look for the rtm. Its available with a little googling.
     
  20. Dufus

    Dufus Senior member

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    AFAIK Linux has been AVX ready since the middle of 2009 so thought it only proper to add a result for that platform too. This was run on a 2500k @ 3.4GHz using Fedora 14 run from the live CD (no installation).

    [​IMG]
     
  21. JAG87

    JAG87 Diamond Member

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    Good info.

    Are there any actual everyday applications that use AVX instructions yet?