A few errors in this article.
First I wouldn't compare the chipset of the x3950 to the power 570 and power 560. The power servers do not have a external chipset in the same sense as the x3950 do.
Try to have a look at this redbook that deals with the big brother of the power 570 the power 595:
Furthermore the new 4.2GHz power 570 with a maximum of 32 Cores is a 4 CEC (building block) system, hence each CEC have 2 CPU boards which each has 2 'sockets', giving it a total of 8 cores per building block.
The only problem I see with these new systems (power 560 and power 570) is that they have can house less memory than the power 550 and the 16 core power 570 per core.
I do think that the power 560 have been overdue for some time. But it is a nice upgrade from the p560Q which could house 16 1.8GHz power5+ cores and only 128GB of RAM.