Asked in Microprocessors
Why your CPU fan goes loud sometimes and goes back to normal by itself what could be the problem?
Your computer adjusts the fan speed depending on the workload it is receiving, this can be due to applications running in the background and operating system tasks that you may not realize are happening but still cause a spike in CPU activity. so to compensate for the extra heat created by the increase in activity the fan runs faster for a short time. if this seems to be happening a lot with little or no visual load on the computer then look for unwanted applications in the start up tasks by typing"msconfig" in the run window. if that still doesn't work consider buying quieter CPU and case fans if you are comfortable installing them yourself.
you should also check to see if you have enough RAM, computers with not enough ram spend a lot of time swapping memory between the hard drive and RAM thus further adding to their workload when multitasking. to check if ram an issue then hit ctrl-Alt-Del next time the fans start to become a problem and look under the performance tab to see if the page file history has had any recent spikes.
hope this helps.