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Former Intel CPU engineer details how internal x86-64 efforts were suppressed prior to AMD64's success
(www.tomshardware.com)
This is a most excellent place for technology news and articles.
See also: ECC memory.
Sometimes for some reason, there's no limit. Like the cheap i3-8100 can use ECC memory
AMD allowed procssors to use ECC memory since Ryzen so the the jig was up.