@beanos  Looking at some of the systems mentioned applicable for Dell's TPM firmware update here, they seem to have launched in mid-2015 to late 2016.  The M4800 seems to have launched in late 2013.  There's no firmware update listed on its Downloads page on the Dell Support site.

Is this something that can be upgraded via a bios update, or does it require different hardware?

I bought my M4800 a year ago (refurbished from Amazon) and I only just replaced it 2 months ago with an older Optiplex 7010 as my main desktop PC (my desktop was just the M4800 on a dock) and neither have TPM so I'll probably have to just stick with Windows 10 for now.

@EricGrover  Two posts above yours I already noted that while there are TPM firmware updates, such as the one I linked in that very post, there does not appear to be such an update for the M4800.  So while it is possible to upgrade at least some TPMs from 1.2 to 2.0, that's not a guarantee, and it seems that no such update is available for the M4800 specifically.

If you can run Windows 10, you can run also Windows 11.

Youy know the rule: Windows is Windows.

But more about this TPM 2.0 problem in next few months when official preview builds start circulating.

Unofficial leaked 11 is already working without TPM 2.0.

I have also few M4800 at home waiting the new version.

Dell precision 4800 is truly remarkable in it's engineering. It updated to windows 11 with tpm 1.2 and works well, it's quick and does the job even better. It's a 11 year old pc but the hardware still held up and now will be up to date till win 11 eol. Amazing 

@Vilder​ how did you install it. I am trying to upgrade it I cannot , it’s failing stating the hardware doesn’t meet the minimum criteria. Tried to install using the registry update hack provided by Microsoft, even that did work.

@Hellosibba​ sorry for late reply. I downloaded the win 11 installer as media from microsoft help site and installed it through a usb. 

Create installation media for Windows - Microsoft Support

Download Windows 11