My computer fan keeps racing. There is no particular time. I could be on any website, or just reading my emails. Does anyone have any suggestions on why. [B]It's doing it now as I am writing this Here's a sample of a log that I just
Kept. Started 4:33 - 4:34, again 4:36 for about 1/2 min, again 4:41 - 4:43, again 4:55 for 1/2 min, again 4:57 - 4:58, 5:01 - 5:02.

As I am writing you this, it last ran for 1 min only. Started at 5:17 stopped at 5:18. Now 5:22 to 5:23. Help.

When is the last time you cleaned your machine? It can be overheating if it has a lot of dust inside. You might want to try that first if you know how or take it in for a good cleaning.

First, suggest you look at the fan and any heatsink and see if they are covered in dust. If so, carefully vacuum or use a canned electronics duster to clear the dust. Also check for cabling or other items that may be getting into the fan. If it still is making noise here are some other possible reasons:

1. Fan bearings are worn resulting in growling noise. This is most prevalent when starting up a cold system that has been idle for awhile. Once spinning and warmed up the noise may dissipate. Fan should be replaced.
2. If the fan speed is controlled by the motherboard (fan will have 3 or 4 wires plugged into motherboard header), the speed can vary based on processor load. Normally any speed changes will be either gradual or in discrete steps. If the ambient temperature inside the case is close to a temperature that would result in a speed increase, in certain circumstances a fan can oscillate between two speed steps as it speeds up to increase cooling and then slows back down once the temperature sensor is cooled and the cycle repeats. Running the computer without the side or top cover can lower the case temperature enough to see if this is the issue.
3. The speed controller on the motherboard is failing. The speed may increase to the fan's minimum or maximum for a short period of time. Result may sound like Morse code.
4. Thermal interface between processor heatsink and processor is marginal due to an air pocket, improperly applied interface material, or a loose retaining clip or screw. To correct, the heatsink and interface material needs to be reinstalled properly.

I'd wager dust or #2.

Thank you for your suggestion. I took my computer to Best Buy geek squad and they cleaned it out with the air compressor can. That did the trick. Like new again - no fan blowing or racing. I will remember to clean it myself once a year.