Or a reason to return it. Fans are REQUIRED in current designs and for reasons of keeping the cost low you find some models have a little more fan noise. And it does change over time due to what apps folk install and more.
The only thing besides the warranty and return is to prop up the back of the machine a little to let more air flow around the unit.
Also, reducing the fan speed is a bad idea. Laptops already have a short life span so this reduces that again.
About a month ago I purchased a dv7 notebook with an Intel i7 processor. Right out of the box, the computer's fan noise was a little more than I'm accustomed to in notebook PCs, and at times of very high CPU usage (gaming, HD video) the noise level could be irritating, making the computer's above-average sound system seem more of a necessity than a luxury.
But recently the fan noise has changed from a loud whir to more of...well, a lawn mower-like rattle. The computer is not overheating and shows no error messages regarding the fan; I'm running Windows 7, the BIOS is current, and the vents are clean. When the fan kicks on max the noise is clearly audible across a big room and there is considerable physical vibration; even when the fan is barely running (which is almost always) there is an out-of-place buzzing or knocking rather than the usual even, quiet hum. However, to reiterate, the core does not seem to be overheating and the processor performance is unaffected, although the bizarre fan noise persists at some level (and cuts in and out) even when the computer is merely idling. It's phasing in and out as I type this, every few seconds.
I don't want to take the unit apart for nothing, since I believe quite a number of components need to be unmounted to reach the fan and CPU.
I've reduced the max CPU capacity to 70%, which is not an ideal solution but seems to help somewhat. Any other suggestions apart from having the fan replaced or just getting a different computer? This is a disappointing situation for less than 30 days off the shelf. I ran a lower-end Toshiba for three years with no fan problems whatsoever (though admittedly plenty of other ones).