Pop gose the fan
Is the device that controls the fan speed, in the fan or on the motherboard? this can be a problem when cleaning a CPU becouse, if fan blade turns too fast the moter of the fan can turn into a generator, if that happon, the fan will still turn on, just not fast enough to start the computer's CPU. Just hold the fan blade still when cleanning. The same gose for PSU.
Are you asking a question or making a statement?
When cleaning fans with compressed air - you should block the fan from spinning so that you don't break em.
Both, I have a computer that has that problem, I need to know where the fans speed control is, So I will know wher to start. I'm sure the PSU is bad, I'm not sure about the MOBO.
Depends on fan, mobo and/or header in use.