No -- the CPU cannot be upgraded/replaced;  it's soldered in.  
My Alienware 17 R3 reports it can't run Windows 11. I have TPM 2.0 up and configured properly, UEFI enabled in the Bios, DirectX 12 installed, 32G of ram and running an 8G Nvidia 1080 Ti in the graphics amplifier, 3 TB of onboard HDD/SSD storage. I'm puzzled. Windows tool doesn't report what it is specifically objecting to. Anyone else getting this?
17 R3, can't run Windows 11?