I'm rebuilding an older server to act as my compile farm. So, digging through my box of RAM to see what I can find that fits the bill.
The documents for the machine indicate (emphasis mine):
DIMMs should be installed in matched sets of four. This enables quad-channel operation and provides the highest memory bandwidth. The sets of four must be MATCHED IN SIZE, RANK and ORGANIZATION. This information can normally be found on the FBD label. For example, the label of each FBD in a set of four might read: 1G 2R x8, in which 1G represents the size of the memory module, 2R represents the number of ranks, and x8 represents the organization.
It goes on to say:
They can also be installed in pairs of two; in this case, the computer will continue to operate, but with a slight reduction in performance. The pairs must be MATCHED IN SIZE, RANK and ORGANIZATION.
Of course, the SPD devices contain far more information than that outlined, above. So, its possible that devices can bear the same descriptive labeling yet not be matched *enough* to satisfy the first (vague!) criteria.
Would not a better way of differentiating between these two (descriptively IDENTICAL) sets of criteria been to refer to "having identical part numbers" in the first case and "compatible *descriptions*" in the second? I.e., there are obviously more constraints at work in the first case that aren't highlighted in the description that is provided (which is identical to that of the second case).[It would also be nice if the user had a way of knowing that he had/hadnot met those criteria as "a slight reduction in performance" is probably not the sort of objective symptom that most users could evaluate!]