Btw...in case anyone asks, I have used memtest on both kits. I ha e completed a 4 passes with 0 errors on both the G.Skill and Corsair memory kits.
The memory itself is fine, this is a board or bios level problem.
Personally I think it's pure bios, for example...I updated to the 2406 bios, I had a ryzen 2600 installed.
Memory worked perfectly, I swap out to the ryzen 3600...boom, right away, no post.
A2 and B2 dumms slots populated...no post, I test each stick in all four dimm slots, B channel non functional.
But A channel working fine...this MUST be a bios level problem.