REVIEW: Intel Core i7-3960X and Intel X79 DX79SI

Lack of competition hurts any market. For example, with the departure of NVIDIA from Intel chipset maker list (solved by licensing NVIDIA IP for $1.5 billion), the semiconductor giant from Santa Clara slowed down the high-end roadmap. For example, the last performance chipset from Intel was launched in November 2008, i.e. exactly three years ago, while the mainstream chipset part went through a billion-dollar recall due to botched SATA controller.

Every wait comes to an end, though. At IDF, Intel showed us what X79 and Sandy Bridge-E would be packing, and was met with quite a few mixed reactions as it simply didn't appear to be a big improvement over Sandy Bridge's P67/Z68 chipset. Today, we will be taking a look at both the X79 chipset and the processor when we review the DX79SI and Core i7 3960X processor. What question is, can Intel surprise?

Technical Details

The Intel Core i7-3960X is the flagship processor of the Sandy Bridge-E release of Intel's Tock cycle of processor development. For those that are unaware, Intel follows a Tick-Tock architecture design philosophy which involves a new architecture followed by an improvement upon that same architecture as a result of a better manufacturing process or some other performance improvements.

However, with Sandy Bridge-E, Intel claims that they are a Tock to the Sandy Bridge Tick. We're not sure how that exactly works, since SNB-E is the original SNB minus the integrated graphics, plus four CPU cores and a doubled memory controller.

The Core i7-3960X will be followed by a Tick next year by the name of Ivy Bridge which should be manufactured on Intel's new 22nm manufacturing process relative to Sandy Bridge's 32nm process.



Getting back to the processor itself, the Core i7-3960X is the fastest and most expensive processor that Intel currently offers to consumers. The processor itself is a 6-core (sexacore/hexacore) design which is built off of the previous quad-core design of the first Sandy Bridge processors. If you look at the diagram, you'll notice that there are 2 unused cores, these two cores are for the server version that Sandy Bridge-E is based off of, Sandy Bridge-EP. In total, Sandy Bridge-E amounts to about 2.27 billion transistors, which is the highest transistor count Intel has ever seen on a desktop processor. Because of this, Intel has decided to put a heavier focus on the L3 Cache (which Intel calls 'smart cache').

The physical Core i7-3960X die has 20MB cache, but only 15MB are enabled for all 6 cores to share. This is in contrast to the original Sandy Bridge processors like the 2600K which only came with 8MB, meaning that Intel has nearly doubled the amount of shared L3 cache.

Since Intel is still on the 32nm manufacturing process for this processor, Intel is forced to make the die bigger in size to accommodate the extra cores and cache and a huge 415mm2 die is the end result. The Sandy Bridge-E processors also all come with support for Quad-Channel memory which means that you have doubled the memory bandwidth from the original Sandy Bridge. Theoretically, with DDR3-1600 you should reach 50GB/s. You can run memory in XMP mode at DDR3-1866 and DDR3-2133, reaching 58.3 and 66.6GB/s respectively.

The added memory bandwidth should serve the added cache and two more cores well and improve performance in applications that thrive from memory and cache bandwidth. These are all in addition to having hyper-threading and Intel's Turbo Boost 2.0 which enables added performance.

There are three members of the Sandy Bridge-E family and they are detailed in the graph below compared and contrasted against the existing Sandy Bridge processors.



As you can see from the pricing, those prices are per 1,000 tray processors, so you can likely expect an extra 10-20% to be tacked on once retail hits. Newegg is already selling them for $1,049. We're already starting to see some bare/non-retail Core i7 3960X's as well.

In the grand scheme of things Intel has brought back their extreme processors with the same pricing structure as they've had in the past with their Core i7 990X and 980X and older extreme processors all priced over $1k.



Architecturally, the Core i7-3960K really isn't much of a departure from the Sandy Bridge that was released earlier this year with the exception of the additional cores, cache and added memory channels. The Core i7-3960X also clocks in lower than most of its predecessors in both the Nehalem, Gulftown, and Sandy Bridge generations. While we're not quite sure why Intel necessarily did this, we assume it mostly has to do with the 130W processor TDP which they probably wanted to remain within. There will be 150W workstation processors (branded Xeon E-Series), and hopefully it gives us more overclocking headroom.

The Motherboard - DX79DSI



The motherboard that Intel supplied us with was the Intel DX79SI - Siler which is based upon the Intel X79 chipset. This chipset was looked at to be as the 'future' one for Intel but it really disappointed a lot of people once they found out that yet another 'new' Intel chipset wouldn't natively support USB 3.0 which is extremely disappointing to a lot of motherboard manufacturers and enthusiasts that just want native USB 3.0.

Bear in mind that Intel had a lot of issues in development of almost every Sandy Bridge chipset, and X79 is no exception. USB 3.0 and Serial Attached SCSI (SAS) are the two features which the company culled from the final release as the whole project ran late. Even so, the chipset supports up to 14 USB 2.0 ports with 6 coming on the rear I/O and 8 coming via USB 2.0 header.

The X79 chipset also supports 6 native SATA ports with only 2 of them coming in the SATA 3.0/6G type, which is not an improvement over the previous Sandy Bridge motherboard chipsets of P67/Z68. This is because Intel has decided that the desktop variant of Patsburg (X79) would not be getting the added bandwidth to the SATA ports that was initially rumored and as a result of that there would be no improvements to storage performance.

If you look at our DX79SI you can clearly see there is a spot on the PCB for 4 more SATA ports, but Intel clearly made the PCBs before they decided to gimp the Patsburg chipset in order to avoid delay into 2012 (which is what happened with Romley, the SNB-E workstation/server platform - which requires SAS and will only debut at the end of first quarter).



The motherboard itself comes with 8 DIMM slots supporting up to 64GB of RAM with a maximum supported OC frequency of 2300MHz. Intel still only officially supports 1600MHz as a native memory clock speed, a missed opportunity as JEDEC made DDR3-1866 and DDR3-2133 official standard as well. The board also comes with a humongous LGA 2011 socket to fit the Core i7 Sandy Bridge-E processors in. It also comes with two USB 3.0 ports in the back and two more USB 3.0 ports via header (3rd party controller). This board is supposed to also support PCIe 3.0 as most Sandy Bridge processors when paired with properly designed motherboards (right switches and resistors) are capable of the 8GT/s that is part of the PCIe 3.0 spec.

Officially, though, this board isn't technically qualified for PCIe 3.0 quite yet so it's sort of a quasi-PCIe 3.0 classification until the classifications are completely verified. The Intel X79 Siler board also comes with 10-channel audio and dual Gigabit Intel LAN which are completely unrelated to the chipset itself but are rather design decisions instead.