Fan noise on Sony (NW270F)

I've had this laptop since early December and have noticed a noise coming from the fan. It sounds like a faint siren sound or whirring. I know that's probably an odd description but that's what it reminds me of. It's not terribly loud but just loud enough to be distracting sometimes.

This only happens when I'm not running a lot of stuff (just using Word for example) but when the fan cycles up that noise goes away. Unfortunately, I'm just using Word about 90% of the time so I hear this noise. It will make the noise for a second, then go away for a few seconds, then return.

I called Sony just to ask if there was some kind of setting (I don't know) that could be changed. They said it sounds like the fan needs to be replaced, and set up a home service call. The guy came, changed the fan and...same noise.

I've found a few references to odd-sounding fans on Sony laptops. But I'm wondering if anyone can confirm that this noise is normal and I'll just have to put up with it?

Thanks

 

I do not have your model computer. Sony has replaced my fan twice in the first year and have extended the warranty to two years.

 

I got the NW380 about 1.5 weeks ago, and the fan is pretty-much silent even when I feel a decent amount of heat at the exhaust port.