Xeon 5600 series brings six-core chips to 2P systems

Intel's gradual roll-out of 32-nm microprocessors has already paid dividends on the desktop, and today, servers and workstations are getting the same treatment.  The chip code-named Westmere-EP in its development is the backbone of the new Xeon 5600 series, a top-to-bottom refresh of Intel's 2P Xeon server and workstation lineups.

The potency of Westmere-EP silicon will be familiar to TR readers who read our review of the Core i7-980X Extreme last week.  (The code name for the desktop versions of Westmere-EP is Gulftown, but they're essentially the same chip.)  Westmere-EP was designed to be a drop-in replacement for Xeon 5500-series (Nehalem-EP) processors, with an upgrade to six cores and 12MB of L3 cache per socket.  The Xeon 5600 series has the same basic clock frequencies and power envelopes as the 5500 series, but obviously, performance should be quite a bit higher with 50% more cores and cache. 

Clock-for-clock performance should be up due to some architectural enhancements in the Westmere family, as well, including a group of seven new instructions, dubbed AES-NI, intended to accelerate common encryption algorithms.  We covered most of these changes in our Gulftown review, but the 2P server market is undoubtedly Westmere-EP's true home.  For instance, some targeted changes should improve virtualization performance, and the chip's memory controller enables support for the low-voltage DDR3 memory now becoming available from major memory makers such as Samsung.  The memory controller supports dual DIMMs per channel at 1333MHz clock speeds, too, where Nehalem-EP supported only one per channel.  The addition of more buffers should allow for higher memory bandwidth at the same memory frequency, as well, according to Westmere's architects.

A new power gate to cut off power to certain parts of the processor's "uncore" section promises lower power draw at idle.  Both sockets must be idle in a 2P system in order for the gate to take effect, however, since both chips will be responsible for memory locations that the other processor may wish to access.

The table below shows the revamped Xeon lineup, with key specs for the different models.  Any products in the 5600 series should be Westmere-based, though some have had cores or features disabled.

Most of the entrants in the table above are fairly straightforward, though several are notable for their strangeness.  Several low-voltage Xeons with two of their cores disabled can fit into 40W power envelopes, which is fairly remarkable.  A handful of others are workstation-tailored parts with 130W power envelopes, including the Xeon X3680, which looks to be essentially the same thing as the Core i7-980X, though with Xeon validation and branding behind it.

No doubt most of the attention from IT administrators will focus on the 95W and 80W parts, which are the mainstream offerings.  Note that many of the 80W Xeons in the 5600 series are quad-core, eight-thread models with two defunct cores.  The six-core parts carry a bit of a price premium.

They should be worth the extra money, though, if our experience with the single-socket Gulftown is any indication.  The combination of more cores and cache added up to excellent performance scaling, even in our scientific computing benchmarks, which had traditionally been limited by memory bandwidth.  Meanwhile, per-socket peak power consumption remained essentially steady versus the 45-nm quad-core Nehalems, yielding a substantial improvement in performance per watt.  If anything, Westmere-EP should be an even more compelling proposition in 2P servers and workstations, where the software infrastructure generally stands ready to take full advantage of 12 cores and 24 threads.  The Xeon 5600 series will face somewhat more formidable competition in the form of the six-core "Istanbul" Opterons, although signs still point to a clean sweep of the performance and power-efficiency contests by these new Xeons.

We'd best not get ahead of ourselves on that point, however.  Several members of the Xeon 5600 series have already made their way into Damage Labs, and we have a full review planned. We're still assembling some of the test equipment, including our fancy new Yokogawa power meter, enterprise-class SLC SSDs, some noteworthy new benchmarks, and the latest hardware from the competition at AMD.  Stayed tuned for a full review in the coming weeks.
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