RDIMM vs UDIMM: Don't mix them — pick one type per channel

Registered (RDIMM) and unbuffered (UDIMM) memory are electrically incompatible. The T5810 can use either, but not both at the same time — mixing them causes boot failure or one set being ignored. Your options: pull the UDIMMs and run only the RDIMMs, or stick with UDIMMs. Pick a lane.