When I was using my PC this weekend, somehow I found that there was some weird noise “DADADA” from the PC case from time to time when I was using Ubuntu 18.04. Because it was irregular noise, it was extremely disturbing and I could not bear with it. The even more weird thing is that when I switched to Windows 10, there is no such noise at all. It is very hard to determine where the source of the noise is, even with the PC case open. But I was still managed to identify the problem and remove the noise in the end.
In this blog post, I will document how I found the problem and how to solve the problem. Hopefully, this will be helpful to users who have similar problems.
I could only hear noise when I was using Ubuntu 18.04. When I switched to Windows 10, the noise is gone. This is weird. Was it because I upgraded some packages in Ubuntu several days ago and it caused this problem?
Fan Physical Inspection
The most suspicious parts are PC fans. I have six fans in total, including two fans in the front panel, one fan in the back panel, and three fans from the water cooler. My ears were not good enough to determine which fan or fans were generating the noise. But it looks like the fans were running smoothly when the noise was generated.
BIOS Fan Settings
Unlike Windows 10 in which I have installed software to control fans, Ubuntu 18.04 does not have fan controlling software. The fans were controlled entirely by the BIOS settings. So I went to BIOS and turned all the fans to full speed. The PC would become extremely noisy as all the fans were turned to full speed. However, I did not hear the weird irregular noise of “DADADA” at all.
The Most Likely Problem
Given all the phenomena observed, I think it is very likely that the fans were throttling somehow, given the temperature in California went higher these days. The temperature was at some threshold where the BIOS decided to increase the fan speed but somehow the temperature drops either due to temperature fluctuation or the fan speed-up.
I changed the fan controlling mode to “manual” in BIOS and played with the fan controlling parameters, such as the fan speed at each temperature, fan speed increase interval, etc. Finally, there was no more weird noise from the PC anymore when I was using Ubuntu.
In Windows 10, the fans were controlled by more sophisticated software from Corsair and the software has different settings to the BIOS fan controller. This is why I had no problems at all in Windows 10.
We Ubuntu users enjoyed solving problems entirely on our own. This time it is certainly a good experience. However, there are more times when the problems could not be perfectly solved. Those problems would often keep bothering us until we found some ways to get around. Getting around is not solving the problem because you often do not know what the source of the problems was, not even mention to find the perfect solution for that.