Hi Riccardo, On Wed, Dec 30, 2020 at 9:57 AM Riccardo Mottola <[email protected]> wrote: > > Hi, > > it is my first time I run linux on an iMac G5 and have some doubts about > its cooling.
There was a regression at some point, did you check: * https://lists.debian.org/debian-powerpc/2020/03/msg00035.html What's your kernel version ? > I noticed that while installing Debian, the fan spins at full speed and > it really deserves the term "windfarm", it is as loud as a vacuum cleaner. > > Once Linux is fully installed, the system runs quiet when doing nothing > (console prompt) and remains quiet when doing several things (also > unexpected ones). > > However, e.g. opening GIMP, the fans whir up, just to slow down > immediately. Then, running a filter is smooth (a bit unexpected). > > What I find strange is that fans run shortly full-speed, then stop after > a second.... or sometimes two! > > I have never run MacOS on this system so I can't tell if this is normal > and if the fan has any intermediate speeds, but this behavior seems strange. > > 1) if the CPU is under "slight load" I would expect the fans to > stabilize to a low speed to keep it cool > > 2) if the CPU has high load indeed, then it probably takes more than > just 1-2 seconds to clear it! > > > in dmesg I see: > > [54879.528590] windfarm: Overtemp condition cleared ! > [55034.523862] windfarm: Clamping CPU frequency to minimum ! > [55034.570358] windfarm: Overtemp condition detected ! > [55036.462349] windfarm: CPU frequency unclamped ! > [55036.513668] windfarm: Overtemp condition cleared ! > > Here it looks that my CPU frequency is temporarily reduced (at the same > time I hear the fan spinning) and if you see the intervals are very > short (only one cycle copy-pasted here, dmesg is much longer) > > > Riccardo >
