Specific Xeon and Itanium processor families the numerical sequences:
Xeon 7000 multi procesor configuration on MB
Xeon 5000 dual processoer configutation on MB
Xeon 3000 single processor
X = Performance
E = Mainstream (rack mount)
L = Power OptimizedIntel's Information
I think W = Workstation for up to 2 processors per motherboard. Anyways hope this helps.