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Linux 4.20 Allows Overclockers To Increase The Radeon TDP Power Limit

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  • #21
    Originally posted by HenryM View Post

    Interesting that just bumping the memory results in such an improvement.
    Yup. This is not a big panel, but I see improvements in Rise of the Tomb Raider too.
    The model with 4GB of GDDR5 is @1750MHz, and the model with 8GB of GDDR5 is @2000MHz. It's marketing, people think they need the model with 8GB of VRAM because it offers more FPS than the 4GB model. In fact, for 1080p gaming, 4GB seems enough, you just need to OC the memory.

    OC is very easy on Linux when you enable the Overdrive, I use the following script:
    Code:
    echo "manual"        > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/power_dpm_force_performance_level
    echo "m 2 2235 950"  > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/pp_od_clk_voltage
    echo "s 7 1420 1150" > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/pp_od_clk_voltage
    echo "c"             > /sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/pp_od_clk_voltage
    And the new pp_od_clk_voltage file looks like this:
    Code:
    0:        300MHz        750mV
    1:        600MHz        769mV
    2:        900MHz        893mV
    3:       1145MHz       1106mV
    4:       1215MHz       1181mV
    5:       1257MHz       1150mV
    6:       1300MHz       1150mV
    7:       1420MHz       1150mV
    OD_MCLK:
    0:        300MHz        750mV
    1:       1000MHz        800mV
    2:       2235MHz        950mV
    OD_RANGE:
    SCLK:     300MHz       2000MHz
    MCLK:     300MHz       2250MHz
    VDDC:     750mV        1200mV
    I tried memory over 2235MHz, but it become unstable.
    Unfortunately, the GPU OC is more restrained without increasing the VDDC.
    Last edited by TumultuousUnicorn; 19 January 2019, 09:13 AM.

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    • #22
      I'm not trying to overclock anything, but get unexplainable "minimal" memory and shader clock values with today's amd-staging-drm-next git head - and a doubled power consumption (12W instead of 6W) for my default 3840x2160 60Hz display mode in comparison to last month's drm-next of the day:

      > cd /sys/class/drm/card0/device

      > xrandr --output HDMI-A-0 --mode 3840x2160 --rate 30
      > echo manual >power_dpm_force_performance_level
      > echo 0 >pp_dpm_mclk
      > echo 0 >pp_dpm_sclk
      > grep -H \\* pp_dpm_mclk pp_dpm_sclk
      pp_dpm_mclk:0: 300Mhz *
      pp_dpm_sclk:0: 214Mhz *

      > xrandr --output HDMI-A-0 --mode 3840x2160 --rate 50
      > echo manual >power_dpm_force_performance_level
      > echo 0 >pp_dpm_mclk
      > echo 0 >pp_dpm_sclk
      > grep -H \\* pp_dpm_mclk pp_dpm_sclk
      pp_dpm_mclk:1: 1750Mhz *
      pp_dpm_sclk:1: 481Mhz *

      > xrandr --output HDMI-A-0 --mode 3840x2160 --rate 60
      > echo manual >power_dpm_force_performance_level
      > echo 0 >pp_dpm_mclk
      > echo 0 >pp_dpm_sclk
      > grep -H \\* pp_dpm_mclk pp_dpm_sclk
      pp_dpm_mclk:0: 300Mhz *
      pp_dpm_sclk:6: 1180Mhz *

      So 60Hz display modes need a lower memory clock than 50Hz - cute.

      (I also verified that the show-stopping bug https://bugs.freedesktop.org/show_bug.cgi?id=102322 is still unsolved. So sad.)

      Comment


      • #23
        Originally posted by Xorg View Post
        See by yourself: https://openbenchmarking.org/result/...SK-RX580444728
        The graphic card is a Sapphire NITRO+ Radeon RX 580 with 4GB of GDDR5.
        The GDDR5 OC is 28% with stock voltage (950mV).
        Sorry, but these results are underwhelming at best. An increase of merely 2.1 FPS in an game engine bench and 16% for synthetic benchmark??? This doesn't seem worth the trouble at all...

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        • #24
          Originally posted by dwagner View Post
          I also verified that the show-stopping bug https://bugs.freedesktop.org/show_bug.cgi?id=102322 is still unsolved. So sad.
          Man, this bug report... feels bad man

          Here we can see that linux users are still second (or even third) class citizens to AMD support...

          Comment


          • #25
            Originally posted by faph View Post
            Sorry, but these results are underwhelming at best. An increase of merely 2.1 FPS in an game engine bench and 16% for synthetic benchmark???
            So I ran a new benchmark on Rise of the Tomb Raider: https://openbenchmarking.org/result/...SK-ROTTR063429
            Ok, the gain is marginal (~4-5%), but it's a "free" gain.

            Originally posted by faph View Post
            This doesn't seem worth the trouble at all...
            Some people like doing overclocking, some other don't.
            I understand wasting time for 5% of gain is not worth the trouble. But that's the game when you do OC, you don't know in advance how much will be the gain.

            Comment


            • #26
              Well. Thanks for the info guys. I'll surely take a look on overclocking when I update my kernel.

              Comment

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