Brands such as ASRock, Gigabyte, Biostar, MSI, and more have compiled lists of motherboards that are compatible with the new requirement, without the need for an external add-on that’s currently difficult to source. Many manufacturers note that while Microsoft lists a TPM 2.0 chip as a requirement for Windows 11, the virtual TPMs built into compatible AMD and Intel chipsets can bypass this requirement. This makes it seem very likely that Microsoft will officially support more aging processors on future builds of the new OS.
While ASRock in particular has an extensive list of boards with older chipsets like the AMD 300 and Intel 100 series billed as compatible with TPM 2.0, it notes that support from Microsoft may vary. Also, many of the officially supported Intel and AMD CPUs are only compatible with the newer chipsets.