I can confirm that ECC DRAM worked as expected on my current AMD Ryzen 9 3900X, an AMD Phenom II x6 1090T that I had in a previous build, and an AMD Opteron 185

I can confirm that ECC DRAM worked as expected on my current AMD Ryzen 9 3900X, an AMD Phenom II x6 1090T that I had in a previous build, and an AMD Opteron 185 that I had in a build before that. The operating system detects the error-correction capability in the memory controller, and errors are properly detected (tested by reducing the memory timings slightly below stable values). I don't think there's a mass-market laptop with ECC support, but AMD's desktop CPUs have supported ECC for as long as I can remember. That being said, it's been an optional feature that is up to the motherboard maker to implement, and not all do.