Yes, you can do a clean install of Win 11.  First, you should back up all your personal files on external media, to be safe.  Don't forget to backup your browser favorites, email address book, etc. Also make sure you have product keys for all the software you installed, eg Microsoft Office. etc.

Then go here and use Microsoft's Media Creation Tool to create the bootable USB you'll need to  the clean install Win 11.  When everything is backed up and you're ready to run the clean install, reboot PC and tap F2 when you see the Dell screen. When BIOS setup opens, change SATA Operation from RAID to AHCI. With the Win 11 USB you created plugged into PC, save the change and exit BIOS setup.

This time, tap F12 when you see the Dell screen and select the option to boot from USB. The Win 11 installer should load, so just follow the prompts. You can select the option to keep personal files, but you'll still have to install all your software again. 

NOTE: Once you change BIOS from RAID to AHCI, it won't be able to boot from the (old) Win 11 on your C: drive again. So make certain you've backed up everything you want to save first.

@RoHe​ OK Thx - I'll try it in few days and let you know. I hope all will be OK.

Just one more - after clean Windows 11 installation what about all Dell software what I have now - originally installed.

@RoHe​ : Thanks!  I may be at this stage with my 8930 as well after all the struggles with my nvidia 4060 upgrade. I was in a "boot/crash/boot/crash" nightmare. Right now I am running windows 10 with selective start and with these two boot drivers stopped. I am OK so far. However, I'd like to get to a clean & healthy state.

You advise "When BIOS setup opens, change SATA Operation from RAID to AHCI"

My C drive is a WD SSD but I also have 2 8TB regular drives.  I thought I read in a different post that one should keep RAID in that case. Is that true?

Thanks for all your help.

P.S: I had W11 upgrade from Dell at one point.

Qn: Will this clean boot require a product key?

@Hokie_Shankar​ Did you solve your problem? 

@Marmadoc​ : Right now everything seems to be working great. No crashes since 6 am. All test software (why so slow, latency monitor) show no issues. CPU running cool.

Things I have not done: Have not installed my HP network printer.  Computer started crashing the last time and "why so slow" mentioned that there was some issue with network. I'm not sure. 

I have enabled secure boot and my third party Nvidia card seems to be working fine. 

I will keep it this way until I know what is causing the boot/crash issue. I have a feeling it is the wdboot - Microsoft Defender Antivirus Boot Driver, but I am not 100% certain

@Hokie_Shankar​ So. It looks like far away from perfect. This is what I'm scared about. Why all of it is so complicated? 

@Marmadoc​ : I am doing a clean install of windows 11 following the directions above. Hope this releases me from the clutches of Dell. Will report back.

Installation went fine. Installed all my software and tested them.  So far so good.  Windows 11 updates are being installed.  Fingers crossed....

A clean install of Win 11 shouldn't require entering the Microsoft product key which is embedded on the motherboard. If Windows says it's not activated after the clean install, log into your Microsoft account and that should allow you to activate Win 11.

Unless those two HDDs are set up as a RAID array, it's OK (best) to change BIOS to AHCI when doing a clean install. Some SSDs don't work well with BIOS set to RAID, notably Samsung and Crucial, but I don't know about WD SSDs. 

Any software that Dell installed, eg SupportAssist, Dell Update etc are free to download from the support page for the PC model.  But do you really need that stuff? But, if you bought Microsoft Office from Dell along with this PC, you will need its product key which should have been included on a paper card in the box.

Also keep in mind that Windows and/or Windows Update might not install all the drivers for you hardware. So if something isn't working or not working properly, look in Device Manager to see if it marks something with warning symbol or if an "Unknown" device is listed.

Then go to the Dell support site, enter your Service Tag (don't post it here) and it should offer you drivers specific for your hardware. Just install the one(s) you need based on what's not working and/or is marked with a warning in Device Manager.

Why would you think WDBoot is causing crashes?

@RoHe​ : Thanks for the feedback.  I have done a clean install after changing the SATA operation to AHCI.

I want keep away from all the Dell "help" if possible.

I bought Office 365 from Micro$oft directly.

I suspected the WDBoot causing the boot/crash/boot cycle because the Event Viewer showed a ton of errors related to Windows security. The computer worked fine in Safe mode and did not crash.   "whocrashed" also said that there was no hardware driver error but a system driver error. So, I disabled the windows security from loading during boot and the crash stopped.