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Raspberry flirc8/16/2023 Modding the official Pi case to have a fan When the CPU throttles, the command vcgencmd get_throttled outputs 0x20002 (the first 2 indicates the Pi has throttled at some point between the prior boot and now the last 2 indicates the Pi is currently throttling the CPU frequency. You can monitor the current temperature in a terminal window by running the command watch -n 1 vcgencmd measure_temp. To install stress, run sudo apt-get install -y stress. After a couple minutes, using vcgencmd measure_temp and vcgencmd get_throttled, I was able to see the CPU start throttling as it hit 80☌ (176☏): But watching videos, scrolling through more complex sites, and switching applications frequently gets the CPU up to 80☌ pretty fast, especially if it's closed up inside a plastic box with no ventilation.įor my more formal testing, I started running stress -cpu 4 to make the CPU do lots of work, continuously. If you're just doing extremely light browsing, reading Wikipedia and the like, it might not hit the point where it throttles. If you run computing hardware at its thermal capacity for long periods of time, this will cause more wear on the parts than if they are run well inside their limits. Second, it indicates that parts inside the Pi (usually just CPU, but likely other parts) are getting hot enough to reach their own internal safety limits. Why is throttling bad? Two reasons: First, throttling prevents you from getting the full CPU speed the Pi can offer, meaning things that you're doing will take longer. ![]() This amount of load is enough to cause the CPU to throttle in less than 10 minutes, in my testing. So imagine if you're truly using the Pi 4 as a desktop replacement, with at least one external USB 3.0 hard drive attached, WiFi connected and transferring large amounts of data, a USB keyboard and mouse, a few browser windows open (the average website these days might as well be an AAA video game with how resource-intense it is), a text editor, and a music player. A firmware update for the Pi 4 may help keep that chip a little cooler, but it will still get hot under load. That area of the board is almost always putting out a pretty large chunk of heat, and the components in this area don't put off heat as well as the metal-bodied CPU.įinally, this image was taken at idle, but if you have any activity on the USB ports, the USB controller chip on the right (that small red spot before you get to the far right of the image) lights up bright white and gets to be 60-70☌ as well. ![]() That's all the power circuitry coming off the USB-C power input. You might notice, however, the bright white areas on the lower left. The CPU/System-on-a-Chip (SoC) was around 60☌ as well, but the metal casing helps spread that heat around the perimeter pretty well, and in the IR image, the heat radiating off the top of the CPU is somewhat masked by the reflective metal surface. Here's a thermal image taken with my Seek thermal imager highlighting the parts of the board generating the most heat after 5 minutes at idle: Not only does the CPU get appreciably hot even under normal load, there are a number of other parts of the board that heat up to the point they are uncomfortable to touch. As long as there was at least a little space for natural convection (that is, with no fan), you could do almost anything with a Pi and not have to worry about heat. And thermal images or point measurements using an IR thermometer usually showed the SoC putting out the most heat. I have been using Pis for various projects since their introduction in 2012, and for many models, including the tiny Pi Zero and various A+ revisions, you didn't even need a fan or heatsink to avoid CPU throttling. The desktop kit includes the official Raspberry Pi 4 case, which is an enclosed plastic box with nothing in the way of ventilation. The Foundation even offers a Raspberry Pi 4 Desktop Kit. The Raspberry Pi Foundation's Pi 4 announcement blog post touted the Pi 4 as providing "PC-like level of performance for most users". ![]() ![]() December 2020 Update: Lo and behold, the Pi Foundation tacitly acknowledges the Pi needs a fan in the official case, because now they sell the Case Fan!
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