Hi all, Sorry for delay I was quite busy last week, > -is this a 3 or 4 pin fan? 3 pin > -is this a 3 or 4 pin connector on MB? 3pin > when you operate pwm1 manually, > - can you see the value with cat pwm1 you did write ther before? Yes good question > - are you sure to be in manual mode pwm_enable=1 ? And another one. > - what do the other pwm1* register read? I studied the documentation update and I think the problem can be caused by two things: 1) the CPU fan is driven by unknown, now obsolete Intel technology Wfm 2) the CPU fan is connected to the superio chip but the base frequency is not correct if the 1) is issue maybe you could connect the fan to another socket, fan2 looks promising. if 2) then you need to check page 118 printed in datasheet Datasheet is here http://www.datasheets.org.uk/datasheet.php?article=2040255 CHeck the register 58 bits D0-D3. You may dump the chip with the following command: isadump -f 0x800 Check the address 0x858, please post the dump here. If you need to change the register 0x58 bits 0-3 then use: isaset -f 0x858 newval (or you might use the mask) do that when the module is unloaded. If you may try the combinations from the table Table 57 ? Different Modes for Fan Or better just send the dump here, and I will tell you what to write to chip. Regards Rudolf