I have the same issue, EVERYONE DOES, it has nothing to do with the bios. The issue is actually that Dell totally dropped the ball with outsourcing it's fan design to a cheap hardware manufacturer in China called Sunon. I took apart my laptop and took out the fan and noticed that it is a cheap peace of plastic that has a wobbly spin. You can test this yourself by touching the fan anywhere but the center and it will wobble. The sides of the fan are lined with teeth that touch the sides of the fan enclosure. When spinning at different speeds it becomes more aparant and as time goes on it will only get worse as the fan pics up dust quite easily making it wobble even more. The cheapest solution is to order a new fan from Sunon, it is only around $10, and they will ship it to you free from China. There are several vendors with various pricing as well, but the good news is that you can do this yourself with the right size star screwdriver and a small philips screwdriver. You can go online and find videos of people taking apart their dell XPS 13's and you can see that the Fan is just about the only thing that's easy to replace THANKFULLY. BUT i CANNOT TELL YOU HOW FRUSTRATED THIS ISSUE HAS MADE ME.