When you put in the other two Procs.
Many of the things I have read... say that there are 2 memory buses. If you have 2 Processor each bus is supported by one of the procs.
If you have a board for 4 procs, you need the 4 procs to see all the memory as they are on the other bank.
Now I have read that the 8 proc boards are similar, but are going to have 4 memory buses, 2 procs per bus. And are needed to see that memory...
But, I have also heard of CPU slots terminators for Intel Stuff, I wonder if that would apply for AMD stuff.