I purchased a RAM upgrade for a customer's Dell PowerEdge T310 from Crucial (click here for RAM info)
I install the RAM and the system does not see it (diag light #1 = No memory modules detected)
The system has an i3 processor and the memory is "registered"; according Crucial's support, registered RAM requires a Xeon processor. Is that correct?
If not, any suggestions?
That is correct, registered memory only works with Xeons. You will need unbuffered memory for the i3.