I have tried some of the suggestions here but the fan keeps running.
I tried Full diagnostics. This did identity several drives and BIOS upgrades. BIOS upgrades took three cycles and this resulted in a second round of driver updates. After this the fan does seem to be able to run at a lower speed - previously it was either off or on full. So perhaps running a full diagnostic + the required upgrades has helped. Allow at least an hour to do that.
At the moment I have only Google Chrome open and the fan is running, but at a slower speed, so far less noisy.
Try installing the Dell Power Manager and adjust the Heat Control to Silent. This dramatically reduced fan noice on my dell xps 15 9560 from 2017.
First, install the Dell Power Manager Service (DPM) 3.0 from Dell's website (link to Danish version, you should be able to change language in the footer). It's a 13.78 MB driver file. During installation you'll be told to download the "Dell Power Manager" from the Microsoft Store.
Open the Microsoft Store (app comes with Windows 10) and search for "Dell Power Manager".
Install the app, run it, navigate to "Heat Control" and adjust to "Silent".
Try it out.
I can confirm that installing Dell Power Manager from the Windows Store has significantly improved my experience with my Dell XPS 15 9560. I recommend installing it from the Windows Store FIRST https://www.microsoft.com/store/productId/9PD11RQ8QC9K because the application will automatically search for and install the drivers it needs on your device. When you launch the app, it can take a while to open (in my experience, over a minute) but it is honestly useful enough to have come as "bloatware" with the product. You can check battery health and automatically lower the battery charge threshold overnight, for example.
But we're here to talk about fan speed. Head on over to Thermal Management, click "Quiet", and all your loud fan woes should be quelled. This is important: do not leave Dell Power Manager on "Optimized" Thermal settings!!! Set it to "Cool" or "Quiet"! I left mine in the optimized state, and my CPU temperature went up to 97 degrees Celsius just from having edge and mail open. However, once set to quiet, it will run quiet. Right now, I'm pushing Edge, Discord, Calendar and Mail across two screens. The CPU is at 60 degrees Celsius (actually lower than before I had this app installed), I haven't had any disconcerting dips in performance like I used to, and the fans are spinning at the minimum level instead of top speed. (yeah, it's not silent, but it would be if I had fewer things open.)
Finally, to clarify, the battery settings can be left on "adaptive"; it's leaving thermal settings on "optimized" that causes problems. I haven't tried thermal's "performance" mode, as I'm afraid I'd melt my CPU.
In my case, I found that the Dell Support Assist Remediation Service was constantly using around 10% of CPU. Once I removed that service, which seems to conflict with more recent versions of Dell Support Assist, the PC is super quiet. A pleasure to work with. See https://www.dell.com/community/SupportAssist-for-PCs/SupportAssist-services-can-they-disabled/td-p/6...
same problem on studio xps 1645.
digged the internet for hours without any succes.
then realized, that the startup screen seems other than usual, 2 black screens at tha start blinking for a half second with some text, and the laptop boots to windows, no dell logo etc.
then made a video in time lapse mode
AND IT SOLVED THE PROBLEM !!!
at the startup simply hold FN and hit sometimes x. and pay me a beer :-))