[zaarn]

What if you reinsert the same RAM stick into the same slot? Minute differences in insertion force and direction can lead to the frequency response of the RAM stick changing. Data paths might now be a micrometer long and require the BIOS to retrain the communication controller to compensate for that.

DDR5 tops out somewhere around 8 Gigahertz clock speed, which means the data signals travel 3 centimeters before the next clock signal arrives. At those time scales it means you're going to have to align those data signals down to the micrometer if you want them to be properly received.

[mnd999]

That sounds awfully fragile to me. Any kind of bump to the case could cause problems?

[zaarn]

It could. Probably not for most minor bumps but reinsertion in the slot is more likely to cause issues than small bumps once insertion forces are being applied constantly. Hence the BIOS has to check.