RPi 3 A+ DietPi-Config Performance Options

Good morning

I’m a DietPi user (7 RPi’s and 1 Asus TB). I use it to crunch BOINC Universe@Home data.

Last DietPi update (v6.30.0) introduced a problem for my 4 RPi’s 3 A+. Performance Options presented in DietPi-Config for these computers are exactly the same as for RPi’s 3 B [‘none’ option is 1200 MHz and ‘high’ is 1350 MHz (please check attached images DietPi@RPi3A+.png and DietPi@RPi3B.png)), nowhere near RPi 3 A+ hardware base frequency: 1400MHz].

CPU utility reports same values for RPi’s 3 A+ as chosen in DietPi-Config’s Performance Options.

Can you please confirm if this is normal or if I’m missing something. I try to get best performance from my RPi’s and ATB.

Thank you.

Best regards,

Paulo Reis

Many thanks for your report.

There is indeed a bug in the code that does not detect RPi 3+ devices correctly. Looks like I missed the “(armv7l)” suffix in device name…
Please do:

sed -i "s/\*'+' /*'+'* /" /boot/dietpi/dietpi-config

That should recover the overclocking options for RPi 3+, although note that we never head any profile for those so only “none” with stock clock is presented. However you can edit /boot/config.txt and adjust the overclocking parameters there. Not sure if there was a reason for no pre-set (I guess we just followed raspi-config), however if you find a stable mode that does not increase CPU temperature regularly >75°C, let me know and I can add it to dietpi-config.

Fixed: https://github.com/MichaIng/DietPi/commit/f7f889dae651ed82ce7c3a19362facc82b669652

Good afternoon,

Thank you for your quick reply, and specially for DietPi.

I will test some RPi 3 A+ CPU settings and come back to you.

Best regards,

Paulo Reis

Good morning,

As promised, here are results from my RPi 3 A+ overclocking tests.

I made over 20 tests ranging from “1400 MHz with -2 over voltage option” to “1500 MHz with 1 over voltage option”. No other changes were made to other parameters.

Only two tests provided stable RPi 3 A+ operation:
a) 1450 MHz with 0 over voltage (3,57 % overclock);
b) 1475 MHz with 0 over voltage (5,36 % overclock).

Stability of case a) was achieved in all 4 RPi 3 A+. Case b) was only stable in 2 of my RPi 3 A+. Please check “RPi 3 A+ Overclocking Feedback a.png” for detailed information.

Images “RPi 3 A+ Overclocking Feedback b.png”- general info -, “RPi 3 A+ Overclocking Feedback c.png” - CPU Loads info - and “RPi 3 A+ Overclocking Feedback d.png” - Temperature info - provide detailed information gathered from RPi-Monitor running on my “RPi 3 A+ A @ 1475 MHz with 0 over voltage”. This machine is running without any problems from 2020/07/26. “CPU Loads” and “Temperature” drops on the 2020/08/10 are due to maintenance reboot. Similar behavior can be verified for my “RPi 3 A+ B @ 1475 MHz with 0 over voltage” and for my “RPi 3 A+ C and D both @ 1450 MHz with 0 over voltage”

Operation temperature is around 50º C. Temperature values change over time reflect decrease of room temperature. This operation temperature is achieved by using 5 cm fan operating over RPi 3 A+ cpu (using adapted RPi case). No tests were done without fan operation so, no temperature limit check was done for all tests made.

RPi 3 A+ run BOINC software for Universe@home project. All 4 cores run at full speed 24h / day. RPi 3 A+ display circuitry is switch off (running /usr/bin/tvservice -o) on all RPi’s.

During my tests some conflicting CPU speed information was provided by different tools:

  1. DietPi-Config (please check image “RPi 3 A+ CPU Speed.png”) reports CPU speed defined in “/boot/config.txt” (please check image “RPi 3 A+ CPU Speed.png”);
  2. Same speed is reported by RPi-Monitor (please check image “RPi 3 A+ Overclocking Feedback b.png”);
  3. lscpu and DietPi CPU utilities report 1500 MHz (please check image “RPi 3 A+ CPU Speed.png”). lscpu is probably reporting CPU spec and not current operation speed (it does the same for my ASUS TB) but RPi 3 A+ base spec is 1400 MHz. DietPi CPU reports current CPU operation speed in all my other RPi’s and ASUS TB.

I have no knowledge to verify the cause of this behavior, present in all RPi 3 A+ (running at 1450 MHz and 1475 MHz).

RPi 3 A+ is a wonderful little board but is very sensible to changes in CPU speed (not due to temperature, but to system stability, from my experience). 3,57 % or 5,36 % is almost no overclock.

I hope this information is useful.

Best regards,

Paulo Reis

Jep, DietPi v6.31 solved the bug that showed RPi 3 non-plus overclocking profiles on RPi 3+ models.

Good morning,

After 6 months of using “1450 MHz with 0 over voltage” and “1475 MHz with 0 over voltage” overclocking settings for my 4 RPi’s 3 A+ it is important to report that even “1475 MHz with 0 over voltage” overclocking setting is unstable (up to 4 crash per machine during this 6 month period), but it does not crash as often as other more extreme overclocking settings. Once more, crash’s are not due to temperature but to system instability.

The only truly stable overclocking setting for RPi 3 A+, from my experience, is “1450 MHz with 0 over voltage”.

I hope this information is useful.

Best regards,

Paulo Reis

Many thanks for your report. I’m gonna add 1450 ARM | 400 core | 500 SDRAM | 0 overvolt as safe/low profile for RPi 3+ models.

Done: https://github.com/MichaIng/DietPi/commit/03a7ff0c72254c02b530883f6ddb1c8193d43f38
Changelog: https://github.com/MichaIng/DietPi/commit/1e36fabe429138999fce0e98231105fcc45585f0