One thing I remembered reading in almost all the posts about the SoC's overclocking abilities was that overclocking the GPU could also lead to increased performance in other areas besides just graphics rendering. So active cooling (or at least a massive heatsink) is a hard requirement when overclocking! Overclock and NVMe storage performance It only took about 3 minutes before the Pi started throttling the CPU to protect itself from overheating. Just to test how quickly the Pi would overheat and throttle without any cooling (and no enclosure), I ran the same benchmark and measured the temperature: It was only about two degrees lower than what vcgencmd measure_temp was reporting. Here's a thermal image of the entire board when it was under the highest load:įor this thermal image, I put a little kapton tape on top of the SoC so the temperature reading would be more accurate. The CPU got the hottest during the first three H.264 compression tests, but was able to keep its cool (with the giant Noctua fan) throughout the other two tests, where it hovered around 40☌. You can see that the temperature never went above 63☌, and I confirmed there was no throttling at any time. You can save that as temp_log.py, then run it with python temp_log.py in Terminal during the benchmarking.Īnd here's the temperature log during the Phoronix CPU benchmarking: With open("/home/pi/cpu_temp.csv", "a") as log: Measuring the Temperatureĭuring the benchmarks, I plotted the temperature by logging it to a CSV file every second with a really simple Python script: from gpiozero import CPUTemperature Note: If you want to run the exact same test suite, you can use the same benchmark shell script I used: pi-general-benchmark.sh. The speedup in each benchmark was almost exactly 28%, which is expected since the clock speed difference between 1.5 and 2.0 GHz is-you guessed it-28%! I wanted to see how the performance at 2.0 GHz compared to 1.5 GHz, so I ran the same three tests using Phoronix that I did in my initial CM4 review, and here are the results: Alternatively, pop the boot volume into another computer (or if using a CM4 with eMMC, set it in mass storage mode using usbboot), and comment out the overclock lines in the /boot/config.txt file. Note: If you set an overclock and your Pi fails to boot, you can plug in a keyboard and hold down the Shift key while booting to disable overclock. Once rebooted, I monitored the frequency as I ran sudo apt-get update, and confirmed it reached up to 2.0 GHz under load: $ vcgencmd measure_clock arm If you want to 'turn it up to 11' (go as fast as the Pi 4 / CM4 can go), set the following options: over_voltage=6 You could also set the gpu_freq= value to up to 750 to boost the GPU clock, but I'm happy with a clean 2.0 GHz and the GPU bits running at their default 500 MHz frequency, so I saved and closed the boot config, then rebooted the Pi with sudo reboot. The highest allowed frequency is currently 2147 (2.147 GHz), though I'm not sure why it's capped at exactly that frequency (the docs and blog posts are mum on that topic). And the arm_freq sets a new maximum upper frequency limit. The over_voltage allows the Pi to give the SoC a little extra power, required when overclocking the CPU frequency. I set that section of the file to contain the following: #uncomment to overclock the arm. So I edited the /boot/config.txt file, and uncommented the arm_freq= line. I wanted to get a nice, clean 2.0 GHz out of my Compute Module it's default clock maxes out at 1.5 GHz, and getting a solid 30% speedup feels pretty good to me-again, assuming an adequate amount of cooling, and a reliable power supply. You can monitor whether the CPU is throttled with: watch -n 1 vcgencmd get_throttledĮditing the config - setting up the overclock.You can monitor the CPU temperature with: watch -n 1 vcgencmd measure_temp.You can monitor the CPU frequency with: watch -n 1 vcgencmd measure_clock arm.Without active cooling, the SoC overheats pretty quickly under load-though you probably don't need this much cooling!Īt some point I'm going to work on a script that controls the fan's speed using the IO Board's built-in PWM-enabled fan controller chip which is accessible over I 2C bus 10. I have a giant Noctua NF-P12 fan that I can plug right into the J17 4-pin fan connector built into the Compute Module 4 IO Board, and for all these tests I let it run full blast, moving a lot of air over the board on my desk. Raspberry Pi Compute Module 4 OVERCLOCKED. There's a video version of this blog post, if you'd like to watch that instead: I wanted to see if the Compute Module 4 (see my full review here) could handle overclocking the same way, and how fast I could get mine to run without crashing. People have been overclocking Raspberry Pis since the beginning of time, and the Raspberry Pi 4 is no exception.
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