They’ll only function in four low-end Intel motherboard chipsets, at least for now.

Intel started shipping its first Iris Xe graphics cards to PC manufacturers on Tuesday—a fantastic milestone for the company’s newfound push into discrete GPUs. But shortly after we covered the announcement, the company delivered a major bummer of a clarification: Intel’s first graphics card won’t work on AMD-powered systems.
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https://www.pcworld.com/article/3604703/why-intels-first-xe-graphics-cards-wont-work-in-amd-systems.html