If you’re switching from Intel’s Core platform to AMD’s Ryzen, you may run into this problem.

Because of limitations in a motherboard’s BIOS, third-generation Ryzen chips may not boot with older AM4 motherboards. The solution? An exchange program that can solve what’s essentially a chicken-and-egg problem for users building their first Ryzen PC.
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Read full post here:
https://www.pcworld.com/article/3409053/amd-has-a-loaner-program-for-third-gen-ryzen-pcs-that-wont-boot.html