A New Chip for a New Year

Sandy Bridge-E will soon have a quad-core derivative released in 2012. Does it make more sense that current LGA1155 SNB CPUs?

When Intel launched the Sandy Bridge-E platform in November, there were three processors listed on the specification sheet.  The Core i7-3960X is the flagship, 6-core processor with the ~$1000 price tag, the Core i7-3930K still had 6-cores but a much lower cost and similar clock speeds and the Core i7-3820 was the only quad-core option and was listed for a Q1 release.  We reviewed the Core i7-3930K in December and found that it offered nearly the same performance as the more expensive unit at about half the price. 

Today we are getting a preview of the Core i7-3820 that will be released likely in early February and will come with a much more reasonable price tag of $285 to fill out the LGA2011 socket.  The question that we must ask then is can the quad-core Core i7-3820 compete against the currently available quad-core Sandy Bridge parts that fit in the widely available LGA1155 socket?  We not only have to consider performance but also the features of each platform as well as the total cost. 

Same Feature Set, New Die

While most of the features of the Core i7-3820 are going to be identical to those of the previous SNB-E processors we have seen, there are some important differences with this chip.  Let’s see what is familiar first.  The Core i7-3820 is based on the Sandy Bridge-E design that works on the LGA2011 socket and the X79 chipset and motherboards currently on the market.  It includes a quad-channel memory controller and 40 lanes of PCI Express that are actually capable of PCIe 3.0 speeds.  HyperThreading is still enabled so you are getting the benefit of being able to run twice as many threads as you have cores. 

There are some very important changes on this CPU as well though starting with a quad-core design.  This directly pits this Sandy Bridge-E part against the currently existing Sandy Bridge processors running on the Z68/P67 chipset and LGA1155 socket.  Also, the L3 cache on the Core i7-3820 is at 10MB, 5MB less than the Core i7-3960X and 2MB less than the Core i7-3930K.  We are basically talking about a processor that bridges the gap between the original SNB and newer SNB-E parts and it creates some interesting battles and comparisons. 

Interestingly, this quad-core SNB-E part is not simply a chip with more cores disabled but instead is a completely new die built on the same 32nm process.  While the Core i7-3960X and i7-3930K have a transistor count of 2.27 billion and a die size of about 435 mm2, the Core i7-3820 is based around 1.27 billion transistors and a 294 mm2 die – a significant reduction. 

Let’s look at the relevant CPU specifications:

  • Core i7-3930K (SNB-E)
    • Cores: 6
    • Base: 3.2 GHz
    • Turbo: 3.8 GHz
    • Cache: 12MB
    • Memory: Quad channel
    • Price: $555
  • Core i7-3820 (SNB-E)
    • Cores: 4
    • Base: 3.6 GHz
    • Turbo: 3.9 GHz
    • Cache: 10MB
    • Memory: Quad channel
    • Price: $285
  • Core i7-2700K (SNB)
    • Cores: 4
    • Base: 3.5 GHz
    • Turbo: 3.9 GHz
    • Cache: 8MB
    • Memory: Dual channel
    • Price: $369
  • Core i7-2600K (SNB)
    • Cores: 4
    • Base: 3.4 GHz
    • Turbo: 3.8 GHz
    • Cache: 8MB
    • Memory: Dual channel
    • Price: $319

AT $285, the Core i7-3820 actually undercuts both the Core i7-2600K and the Core i7-2700K while offering more cache, higher base and turbo clock speeds as well as twice as many memory channels.  The downside is that your X79 motherboard is going to cost more – base X79 options start around $220 while you can get Z68 motherboards for just over $100, $150 for an "enthusiast-class" option. 

Original Sandy Bridge on the left, new Sandy Bridge-E on the right

Another interesting difference with the Core i7-3820 and the other three CPUs listed above is that it is NOT a fully unlocked processor.  Like other Turbo Boost enabled processors in Intel’s Sandy Bridge processors the i7-3820 can be set to a multiplier that is four steps higher than the top Turbo frequency.  So, out of the box, the quad-core SNB-E part will be able to run at 4.3 GHz (single core active), 400 MHz higher than the 3.9 GHz top default Turbo frequency.  There are ways to get higher than this with the 3820 that we’ll cover in our overclocking page a bit later. 

Our testing configuration for this testing was identical to that used in the previous Sandy Bridge-E review. 

Highest clock speed with all cores in use

Highest clock speed with a single core in use

  • Intel Core i7-3820 (Sandy Bridge-E)
  • Intel DX79SI X79 Motherboard
  • Intel water cooler
  • 4 x 2GB DDR-1866 Corsair Vengeance (running at DDR3-1333)
  • Intel X25-M G2 160 GB SSD
  • GeForce GTX 285 Graphics card
  • PC Power and Cooling 1200 watt PSU
  • Windows 7 SP1 64-bit

What are the key comparisons do we want to watch out for? 

  • Core i7-3930K vs Core i7-3820 – In the battle of the $285 and the $555 Sandy Bridge-E processors, we know who should win, but is it by enough to warrant the price difference?
  • Core i7-2600K vs Core i7-3820 – Does the updated architecture of Sandy Bridge-E make any performance differences thanks to the larger cache, additional memory channels and slightly higher clock speeds?  This will help us decide if users on a moderate budget would be better off with LGA2011 or LGA1155 platforms.
  • Core i7-3820 vs AMD FX-8150 – Okay, let’s give the Bulldozer architecture yet another try here especially considering that they are so similarly priced!
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