Answer
Laptops are hot, and get hotter if you block the ventilation holes, frequently on the bottom. unfortunately they are better suited to hard surfaces, rather than laps, carpet, etc. some seem to require external cooling devices due to their design.a bad fan can be noisy, or it could just be a normal fan "revving up" to try to combat the increased heat from blocked ventilation.i suspect a cooling fan that needs replaced, the bearings can go bad and make lots of noise, then fails entirely. check with the blokeufacturer, sometimes this kind of failure is covered by recalls. the other suspect (less likely) is a hdd that is physically sick and about to die, in this example the whole laptop will vibrate when the noise occurs.it may be as simple as blowing out the the dust with a can of compressed air through the vents. or it may be necessary to replace the fan.it could also be the heatsink is gunked up with dust as well causing the fan to run faster and more often. particularly if you have pets.some fans are easy to get at with a compartment on the bottom that actually unscrews and drops the fan out. but most require to at least removing the kb and some you will need to remove the display, kb and palmrest. you will most like need to order a replacment fan from the blokeufacturer since they are usually model specific.
