@rtubaishat 

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https://aka.ms/GetPCHealthCheckApp

PC Health Check App will give the reasons why WIN11 is not supported. A utility by Microsoft to check for compatibility with Windows 11 for any device. By using this software you can easily tell if your PC is eligible for a free upgrade or not. With hardware requirements required to update to  Windows11.

Also:  Microsoft shows why Windows 11 needs TPM – even if some PCs are left out in the cold 

It's a matter of Microsoft making a decision, whose main purpose is to get more new PCs sold, in short order. You can estimate, maybe 600 million new PCs worldwide, within no more than 4 years. The vast majority with a Windows OS. The original poster asked "why," and he didn't really get an answer. The "why" has never been spelled out by Microsoft, in any credible way.

In fact, both the 6th generation Intel Core processors of the OptiPlex 7040, and the 7th generation of the OptiPlex 7050, do work very well with Windows 11. I've had it running on my Intel Core i7 6700 for well over a month now, with no issues. These Intel processors do support all of the hardware security features that Microsoft requires, plus more. All along, my OptiPlex 7040 has had UEFI BIOS, secure boot, and TPM 2.0 enabled, in Windows 10.

Since then, I also enabled virtualization based security (memory integrity), system management mode security mitigation, and trusted execution mode, which are not strictly required for Windows 11. All of these options already exist, in the OptiPlex 7040 and 7050.

My problem is this. Dell is not providing updated device drivers, for my OptiPlex 7040, that are clearly marked compatible with Windows 11. Yesterday I crossed my fingers and installed an updated graphics driver, from Dell. It took some time to install itself completely, creating some lag there while the disc drive was flashing away, but then settled down to nice fast operation.

I realize that Dell has little to gain, from people like me who are using Windows 11, before buying a new PC. But, you know, most of us would probably willingly pay some fee, to have access to such updates.

• My Dell optiplex 5070 has an i5-8600t processor which is a 8th gen cpu

health check says my processor is not fast enough for windows 11

I think the health check is wrong.  The 5070 is on the approved list for Win11.  Your CPU also has the minimum system requirements exceeded.  I'd try downloading/installing/etc. anyway unless for some reason the health check blocks it.

Another user has Win11 on their 7020 or 9020 and proved it with screengrabs.  Both 7020 & 9020 have 4th gen CPU's.

Windows 11 specs, features, and computer requirements 

Hi @Seattle57,

I also want to make sure the bases are covered and doesn't affect the health check, or affect Win11 installation.  I take it TPM 2.0 is enabled in BIOS?

How to enable the TPM (Trusted Platform Module) 

You can make a USB 2.0  32 gig FAT32 installer and get 11 to install by skipping the TPM and CPU checks.

HOWEVER 4 gigs of ram is required meaning you need at least 8 because with 4 the INTEL Video Steals from System ram and you cant get that back.

Once you make the 11 USB go into the sources folder and delete the appraiserres.dll file. Restart and install clean with secure boot off in bios.   Reboot on the USB 2.0 flash drive and make sure your cables are disconnected from online or your router is OFF.

You MUST create a Microsoft Account if you are WIN11 Home but you do not need a microsoft account for WIN11 PRO so you can create a local OFFLINE account.  It will try to trick you into consent to spy on you several times after that when you go online to activate.

There were some problems with Windows 11 Health Check erroneously reporting CPUs that were not compatible. Those CPUs generally had a base frequency of slightly less than 1 GHz. A BIOS update seemed to have corrected the problem. But it is possible that there are still problems. You can install using the media creation tool here (second choice) and that will bypass the CPU check during installation. Also the Installation Assistant on that page is basically the update route. Also this page may help.

The strange thing about the second link is that MS will not allow an update to systems that are not compatible. BUT that page has a link with a registry modification, that MS themselves published, that will allow installation on a system with a non- compatible CPU or has TPM 1.2. Go figure.

Is it possible to upgrade the 7050 to an 8 Gen or better CPU?