The new laptop: Dell Latitude 5490, i5 8th gen, 8gb ram, 256gb ssd, Windows 10.

The problem: The fan noise is inconsistent. I was browsing the web, and it was quite, as it should be. Then, all of a sudden, it became much louder and much more audible, to the point of it being quite a distraction. I've used it for 1 hour now, and this has happened twice. I also check the Task manager every time the fan noise shoots up, and there's nothing to be seen: it's just my browser taking up CPU and memory at a standard level.

The question: Why is the fan noise inconsistent, and what can I do to fix it? Audible noise when merely web-browsing is a deal-breaker for me, and I checked before buying the laptop, and it shouldn't be audible for web-browsing.