[NAME]  - I suspected it was the fan... Since your PC is new, maybe Tech Support will replace the fan for you under warranty -hopefully- with one that's quiet(er), and/or at the least, make sure the fan is properly/securely mounted inside the AIO. You could install Speccy (free) and configure it to load at every boot. It can put an icon in the notification area of the taskbar showing CPU temps all the time so you can monitor the temp when you hear the fan kick in...   
In February, I bought an Inspiron 5400 AIO all-in-one. A couple weeks ago, it started making a noise like a drive running hard. It's intermittent, and mostly seems to happen when it's accessing resources - a webpage loading with lots of graphics or opening a large file - when I have other options open and running. It didn't do this for the first month, so I'm concerned that it could have an issue that needs attention. Is this normal? My Inspiron 5570 laptop occasionally makes a similar noise when its resources are stressed, but not as regularly as the all-in-one. Thoughts? 
All-in-one drive noise