If you are a normal desktop user or even a power user with plans to run at over 4GHz, the vanilla LGA-1155 Sandy Bridge platform is good enough. You get some of the fastest CPUs on the market today paired with reasonably priced motherboards and the ability to use Quick Sync to transcode video...er...quickly. If that's not enough, Intel launched a higher end platform last month: the LGA-2011 Sandy Bridge E.

Take a regular Sandy Bridge, add PCIe 3.0 support, increase the number of PCIe lanes that branch off of the CPU (from 16 to 40 lanes), double the number of memory channels (4 x 64-bit DDR3 memory controllers) and you've got Sandy Bridge E and its LGA-2011/X79 platform. SNB-E is currently available in two forms: a $999 6-core Extreme Edition part (Core i7 3960X) and a $555 6-core unlocked version (Core i7 3930K). Neither is exactly cheap but if you need the PCIe lanes, core count and memory bandwidth, they are your only ticket.


LGA-2011 SNB-E (left) vs. LGA-1155 SNB (right)

Sandy Bridge E is a fairly niche platform to begin with, but what about the niche within the niche (extremeception?) of users who just need the LGA-2011 platform but not necessarily a 6-core behemoth? For those users, there's the Core i7 3820:


LGA-2011 SNB-E (left) vs. LGA-1155 SNB (right)

The Core i7 3820 is the first (and only) quad-core Sandy Bridge E CPU. It's so new that the chip isn't even available for sale nor will it be until early 2012. Unlike the relationship between the 3960X and 3930K, the 3820 is an entirely new die.

The chip features four Sandy Bridge cores and is paired with a 10MB L3 cache, giving it a slight advantage over the highest end LGA-1155 Sandy Bridge CPUs on the market today. The result is a die that's bigger than a regular SNB but significantly smaller than a 6-core SNB-E:

CPU Specification Comparison
CPU Manufacturing Process Cores Transistor Count Die Size
AMD Bulldozer 8C 32nm 8 1.2B 315mm2
AMD Thuban 6C 45nm 6 904M 346mm2
AMD Deneb 4C 45nm 4 758M 258mm2
Intel Gulftown 6C 32nm 6 1.17B 240mm2
Intel Sandy Bridge E (6C) 32nm 6 2.27B 435mm2
Intel Sandy Bridge E (4C) 32nm 4 1.27B 294mm2
Intel Nehalem/Bloomfield 4C 45nm 4 731M 263mm2
Intel Sandy Bridge 4C 32nm 4 995M 216mm2
Intel Lynnfield 4C 45nm 4 774M 296mm2
Intel Clarkdale 2C 32nm 2 384M 81mm2
Intel Sandy Bridge 2C (GT1) 32nm 2 504M 131mm2
Intel Sandy Bridge 2C (GT2) 32nm 2 624M 149mm2

There's a small improvement in base clock frequency over the fastest SNB (3.6GHz vs. 3.5GHz) but max turbo remains unchanged at 3.9GHz. For single threaded applications the 3820 should be just as fast as a Core i7 2700K or a 3960X. The same is true for if all heavily threaded workloads, at least when compared to other quad-core parts (the 3960/3930 still maintain an advantage because of their two additional cores).

Processor Core Clock Cores / Threads L3 Cache Max Turbo Max Overclock Multiplier TDP Price
Intel Core i7 3960X 3.3GHz 6 / 12 15MB 3.9GHz 57x 130W $990
Intel Core i7 3930K 3.2GHz 6 / 12 12MB 3.8GHz 57x 130W $555
Intel Core i7 3820 3.6GHz 4 / 8 10MB 3.9GHz 43x 130W $285
Intel Core i7 2700K 3.5GHz 4 / 8 8MB 3.9GHz 57x 95W $332
Intel Core i7 2600K 3.4GHz 4 / 8 8MB 3.8GHz 57x 95W $317
Intel Core i7 2600 3.4GHz 4 / 8 8MB 3.8GHz 42x 95W $294
Intel Core i5 2500K 3.3GHz 4 / 4 6MB 3.7GHz 57x 95W $216
Intel Core i5 2500 3.3GHz 4 / 4 6MB 3.7GHz 41x 95W $205

There's no on-die GPU, no heatsink/fan in the box and this isn't a fully unlocked part so the 3820 is actually cheaper than most of the high-end Sandy Bridge CPUs: it's priced at $285. If it weren't for the fact that you'll still need to spend over $200 on a motherboard I would say that the 3820 is a steal.

Overclocking

Let's start with the basics. All Sandy Bridge CPUs are clock locked by default, they can't operate at frequencies other than what they're sold at. There are two exceptions to this rule. All Sandy Bridge CPUs that support Turbo Boost are partially unlocked. Not only can they turbo up to frequencies that are higher than their default clock, but they can also be overclocked to frequencies even higher than their turbo speeds. By default, all Turbo enabled Sandy Bridge CPUs can be set to run at up to four bins (4 * bclk or 400MHz by default) higher than their standard turbo frequencies:

The second exception is any of the K or X-series SKUs. If your Sandy Bridge model number ends in a K or X, then the chip is fully unlocked and can be overclocked up to 5.7GHz using only clock multiplier adjustments.

The Core i7 3960X and 3930K fall into the latter category, which makes overclocking them a breeze. The 3820 on the other hand is partially unlocked, which means that we can run it at up to 4.3GHz using multiplier adjustments alone. Note that the 4.3GHz limit only applies to the 1-core active state, in the worst case scenario of all cores active with no room to turbo the highest operating frequency of the chip when overclocked would be 4.0GHz.


The max 3820 overclock without touching bclk settings

While these aren't bad targets, they're not all that exciting either. Thankfully Sandy Bridge E makes it even easier to overclock through the use of a few higher bclk frequencies. By default Sandy Bridge uses a 100MHz bclk, but SNB-E allows for 125MHz, 166MHz and 250MHz options as well. The 166/250MHz settings are a bit too aggressive, but the 125MHz bclk setting proved to be the perfect companion for the 3820.

Intel's DX79SI makes it extremely easy to overclock, especially with the latest BIOS update. There are built in overclocking profiles for each bclk setting that you can choose from. I simply selected the 1.25x (125MHz) profile option and then went through the list of target frequencies until I found one that seemed promising. I also went in and tweaked some of the settings myself to get a bit more clock speed (4.63GHz is the fastest profile this board allows by default) and improve stability. In the end I was fairly pleased with what the 3820 could do: 4.75GHz with Intel's RTS2011LC closed loop cooling system.


Now we're talking

I couldn't get the 3820 as stable as I would like at 4.88GHz and 5GHz was unfortunately out of the reach of my sample. I can't really complain about 4.75GHz from a $285 chip though, especially without resorting to anything too exotic from a cooling standpoint. Overclocking is also extremely effortless thanks to the new bclk options on SNB-E. Although the Core i7 3820 isn't an unlocked part, that doesn't limit how far (or how easily) it can be overclocked. A big part of the ease of overclocking is due to how good of a job Intel did on the DX79SI BIOS options, but from what we've seen the third party boards also do a decent job of simplifying the process.

Overclocked: x264 HD Benchmark - 2nd pass - v3.03

Overclocked Power Consumption - Load (x264 HD 3.03 2nd Pass)

The Test

To keep the review length manageable we're presenting a subset of our results here. For all benchmark results and even more comparisons be sure to use our performance comparison tool: Bench.

Motherboard: ASUS P8Z68-V Pro (Intel Z68)
ASUS Crosshair V Formula (AMD 990FX)
Intel DX79SI (Intel X79)
Hard Disk: Intel X25-M SSD (80GB)
Crucial RealSSD C300
Memory: 4 x 4GB G.Skill Ripjaws X DDR3-1600 9-9-9-20
Video Card: ATI Radeon HD 5870 (Windows 7)
Video Drivers: AMD Catalyst 11.10 Beta (Windows 7)
Desktop Resolution: 1920 x 1200
OS: Windows 7 x64

 

Windows 7 Application Performance
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  • keristerzt - Thursday, December 29, 2011 - link

    Of course, the X79 is support up to 40 lanes, that means you got native 16x16x bandwidth for both cards, this is a great deal, plus it has impressed me by it 4-channel of memory, brings up the bandwidth to 51.2GB/s Reply
  • tech6 - Thursday, December 29, 2011 - link

    As you can see by the benchmarks, the extra PCI and memory bandwidth will make no difference to your gaming experience whatsoever. Games simply don't require more than SB delivers. However, if you want to be the first kid on your street that has a SB-E then go for it. Reply
  • MySchizoBuddy - Thursday, December 29, 2011 - link

    Compute will benefit from it. best option for compute is for 8 full x16 PCI-e.
    tyan provides a motherboard with those features for Compute servers.
    Reply
  • DanNeely - Thursday, December 29, 2011 - link

    The benches anand did are meaningless for a GPU comparison. Where LGA2011 might perform better is on 3/4 GPU setups, but these numbers are for a single 5870. Reply
  • cactusdog - Thursday, December 29, 2011 - link

    This is why Intel didnt release the quad core 3820 with the initial launch of SB-E. It gives us an easy comparison with the 2600K and it highlights just how poor SB-E performs when compared to normal SB.

    I've always been a supporter of the highend but its hard to like SB-E unless you're prepared to spend $600-$1000 on a 6 core CPU, even then it aint great.

    Reply
  • SlyNine - Thursday, December 29, 2011 - link

    Not sure I agree with that, It does slightly better in the benchmarks and the 6 core CPU's for 600$ sounds about right to me. Reply
  • Taft12 - Thursday, December 29, 2011 - link

    If you think $600 for a 6-core CPU sounds about right, you're going to lose your shit when I show you the Phenom II X6 prices! Reply
  • nevertell - Thursday, December 29, 2011 - link

    Well, you're going to lose your shit when I tell you that they are discontinuing all the stars based phenom II x6 processors. Reply
  • iLLz - Thursday, December 29, 2011 - link

    I'm not going to lose anything! The Penom II x6 performs worse than Intels Quad Cores so pffft! Reply
  • SlyNine - Thursday, December 29, 2011 - link

    Then you're going to lose your shit when you see this 280$ CPU beating the crap out of the Phenom II X6.

    Seriously lets keep it in context here. Thats like saying I can buy 6 atom CPU's for 50$ so paying for a phenom is too much.
    Reply

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