Intel soundlessly emits Broadwell Xeon E5-4600 v4 quad-socket chips
She's built like an E5 but handles like an E7
Just because Intel doesn’t make a lot of noise about a product does not mean that it is not important for the company. Rather, it is a gauge of relative importance, and with such a broad and deep portfolio of chips, not everything can be cause for rolling out the red carpet.
So it is, as usual, with the Xeon E5-4600 processors, the variant of Intel’s server chips that has some of the scalability attributes of the high-end Xeon E7 family while being based on the workhorse Xeon E5 chip that is used in the vast majority of the servers in the world.
In essence, the E5-4600 is a variant of the E5-2600 that has a slightly different NUMA configuration. With the E5-2600, the two QPI links on the processor are cross-coupled, providing high bandwidth and low latency between the two sockets, and offering near linear scaling across the compute and memory. For all intents and purposes, the two-socket machine looks like a massive single processor to the systems software. With higher levels of NUMA, it can take two, three, more hops between sockets for data to be moved.
With the E5-4600s, the four chips are linked in a ring with each processor being directly linked to two adjacent processors but needing two hops to get to the fourth. This adds some latency in memory access across the NUMA cluster, which is important for some (but certainly not all) workloads. With the Xeon E7-4800s, each chip has three QPI links, so the four chips in a quad-socket box again are tightly linked and it only takes one hop to get from one socket to the other.
(With the E7-8800, two rings of quad sockets are cross-connected and a quarter of the time again it takes two hops to get from one socket to the other, but three quarters of the time it only takes one hop or no hop at all because you hit the target right on the first try.)