Question: are udimm and dimm compatible?
Answer: Yes! one can insert DIMM RAM in UDIMM slots only when both are of the same type i.e. DDR1/2/3/4/5. what I mean is one can insert DDR3 DIMM RAM in DDR3 UDIMM slot. If DDR3 DIMM is going in a DDR4 UDIMM slot, it is simply not possible.