RPi 3 - Reduce power consumption and heat. Server usage.

[fourdee4d]

For server usage, power consumption and heat can be reduced on the RPi 3, without effecting performance.
By lowering GPU related clocks, we can reduce the overall power consumption by 0.2W~. As less power = less heat generated on the ARM, you should also see a benefit of reduced overall heat.
We can also reduce the power consumption further by 0.1W~ by setting headless.

In /boot/config.txt, set the following entries:

Code: Select all

gpu_freq=150
h264_freq=25
isp_freq=25
v3d_freq=25

Here are my test results:

• RPi 3
• Performance CPU gov echo -e "performance" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
• Idle (see attached image for htop process list)
• Ethernet uses 0.1w when active.
• Baseline energy consumption = 2.1W
• gpu_freq=150
  h264_freq=100
  isp_freq=100
  v3d_freq=100
  2.0W
• gpu_freq=150
  h264_freq=25
  isp_freq=25
  v3d_freq=25
  1.9W
• Headless:

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  fbset -xres 16 -yres 16 -vxres 16 -vyres 16 -depth 8
  /opt/vc/bin/tvservice -o

  gpu_freq=100 #Results in no output on HDMI
  h264_freq=25
  isp_freq=25
  v3d_freq=25
  1.8W

This assumes core_freq on the RPi 3 has no effect on CPU performance (eg: like the RPi 1/2 which effects L2 cache): http://elinux.org/RPiconfig.
core_freq = For models prior to the Pi2, this has an impact on ARM performance since it drives the L2 cache.

[jahboater]

Thanks for that interesting post.
Why do the fbset - is it just to reduce the memory used?

[fourdee4d]

Thanks for that interesting post.
Why do the fbset - is it just to reduce the memory used?

RPi memory is shared with GPU. So by reducing the FB (framebuffer) size, reduce bandwidth used by GPU/FB: viewtopic.php?p=105008#p105008

[jahboater]

Great tip thanks! As someone in the post says even if its only a small improvement, sticking a line in /etc/rc.local is free and simple.

I changed it to: fbset -g 16 16 16 16 8

[vale88]

Thanks for sharing. I am always looking for ways (such as sleepy pi) to reduce power usage with Pi.

Valentin S.
Java developer
Interests: JavaFX, NetBeans and Raspberry Pi

[fourdee4d]

Thanks for sharing. I am always looking for ways (such as sleepy pi) to reduce power usage with Pi.

If performance isnt a factor, you can reduce power consumption further by limiting the max CPU clock.

Setting the powersave governor will limit the device to 600mhz:

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echo -e "powersave" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

You can set this in DietPi-Config if your using our optimized image. Applied automatically during boot:

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