Hi, thanks for your reply and your help! > What motherboard it is? Asus A8V-E SE? Can you please send dsdt table here? The mainboard is labeled A8V-E and the box it came in is labeled A8V-E SE. > cd /tmp > cat /proc/acpi/dsdt >dsdt.bin > iasl -d dsdt.bin Unfortunately there is no /proc/acpi/dsdt on my system. Can you tell me what is missing? A kernel option? > If you go to BIOS, is Q-fan enabled? What is your settings there? Yes I know that Q-fan is enabled. A (more hardware savvy) friend of mine configured this. The target temperature is 40?C with a tolerance of 3?C. A setting I do not understand is called "fan duty cycle" and is set to 11/16. My fan used to spin between 3000 and 5000 rpm. However the system somewhen[1] stopped doing so and now merely sits on about 3500 however hot the cpu is. This is also bad, because I cannot run the system at full speed with work for a longer time. Helmut [1] Kernels I used: 2.6.18, since March 2007 2.6.20.1, since January 2.6.23.14. According to munin graphs the system stopped spinning higher than 4000 rpm around September.