Swapping RAM, system wouldn't boot with tested RAM, found a quick fix -- what gives?

Hello. I've been building a "new" computer out of 2022 Rocket Lake parts. No problem with that. It just needs some fan-deployment tweaks and minor refinements and good to go. I chose to swap the RAM from my old "super-duper" system which had 4x16 64GB of G.SKILL 3200 GTZR RAM -- that is, this latter went into the ROCKET. I put 16 GB of 2x8 GTZR into the old system, tested it most of the morning -- good to go. I had another set of 2x8 GTZ -- same specs otherwise just no glitzy lights. It had been tested, previously was working in the ROCKET. The old system (KABY LAKE) wouldn't boot! I had handled the RAM carefully, put them in the system with AC unplugged and all powered down. Nothing could've happened, but -- who knows? I did a quick search online -- it was Reddit. Big discussion. Then, someone suggested "pull all USB devices -- including keyboard and mouse, then try to boot. If it boots, plug the USB plugs back in the sytem." This apparently worked for the people in... Read more