Review Index:

Intel Core i7-3820 Processor Review - Quad-Core Sandy Bridge-E under $300

Author: Ryan Shrout
Subject: Processors
Manufacturer: Intel

Overclocking the Core i7-3820

As I mentioned on the first page of this review, overclocking on the Core i7-3820 is a bit different than with any other Sandy Bridge processor out there.  Because it is not fully unlocked, the multiplier is limited to 43x, about the same as the non-unlocked Core i7-2600.  Unlike the original Sandy Bridge though, Sandy Bridge-E allows us to use "straps" or bus speed multipliers that still operate with the 3820.  

If you remember overclocking via the base clock on SNB, going above 105-107 MHz tended to be pretty difficult.  Intel addressed this on SNB-E by offering "straps" that basically act as multipliers on the base clock.  So on most motherboards you will see the option for a strap of 125 MHz or 1.25x, depending on the vendor, and that is how we were able to get past the multiplier limit of 43x to see higher overall speeds.

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On Intel's DX79SI motherboard, they call it the "1.25x Profiles" that puts the processor base clock at 125 MHz and sets the voltages accordingly.  Intel's motherboard engineers actually did a very good job making this process easy as it only took a couple of BIOS changes to make it happen.

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These are the result voltage and limit changes set by simply enabling the 1.25x profile on the DX79SI motherboard - again a very positive overclocking experience!  When you set this mode though there aren't many options that Intel allows you to change - what you see if what you get. 

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The base clock speed brought us to a 4.5 GHz clock rate...

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Though I found that moving to a 37x multiplier was the highest I was able to go without being able to adjust the voltage any higher.  This clock speed worked even with all the cores enabled, so we are essentially seeing a 700 MHz boost over the default settings of the Core i7-3820! 

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In our CineBench tests, the default scores were 6,134 and 24,352 respectively and we see the above results are 24% and 22% faster.

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Our previous POV-Ray result was a score of 5,267, giving the overclocked Core i7-3820 a more than 23% performance boost.

While overclocking on the "partially unlocked" processor was a bit more complicated, hitting 4.63 GHz on the CPU is pretty impressive and takes the $285 processor much closer to the performance of the 6-core Sandy Bridge-E variants at their default settings, at least in those highly threaded cases.  For fewer threads, these high clock speeds would be able to beat out the default configurations of basically any CPU on the market.  Not bad for under a 3-spot. 

Keep in mind that this overclocking definitely raises the power consumption and TDP of the processor.

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At the overclocked speed of 4.63 GHz the Intel Core i7-3820 uses 90 additional watts of power - that's a 50% increase for the entire system!  Make sure you have a good cooler (we used the Intel water cooler kit) to make sure things stay out of the red.

January 4, 2012 | 10:30 AM - Posted by Jared (not verified)

Great Work PCPER.

January 4, 2012 | 11:12 AM - Posted by Prodeous (not verified)

Very nice review. I will admit makes me want to get it over the 2600K.

With regards to the review. I was wondering if there is a way to make the result charts more readable?

The main thing is better grouping of Intel and AMD cpus? I know this is more or less add the newest CPU at the top, but when I jump from page to page and try to compare it to other CPUs it makes it difficult to quickly compare between them.

Possible area of improvement is just colour code it. AMD green, Intel Blue, currently tested Red? Or any other colour scheme.

Beyond that I'm curious about the Blender benchmarks, especially with Blender 2.61 having better multithreading and new rendering engine called Cycles which is fully ray tracked engine unlike current.

What ever you guys do or not do I just want to say. You guys are doing an amazing job.

Polish Canuck - Prodeous.

January 4, 2012 | 01:10 PM - Posted by Ryan Shrout

Prodeous, thanks for the comments. I think you are right on the graphs and it is something we have tried to figure out in the past but honestly, my Excel-foo is just too weak... We'll try again soon!

As for Blender, we are going to completely re-do our CPU test bed soon and I'm sure we'll update it then.

January 4, 2012 | 02:00 PM - Posted by Nebulis01

I think this will be a decent way to upgrade from my Q9650 :)

Thanks for the great review!

January 4, 2012 | 05:31 PM - Posted by hechacker1 (not verified)

Any thoughts on the continued support of LGA 1155 vs 2011? In the long term, I'd think the 2011 platform is a better choice. You get PCI-E 3.0 for next gen GPUs, and a socket that potentially carries you onto a Ivy-E chip with 8-cores? A lot of speculation I'm sure.

Care to comment? btw love the podcast.

January 4, 2012 | 06:07 PM - Posted by Dreadteir

As a enthusiast, I think I like what I see in the SNB-E.

For my build later this year I was looking at the 2600K with a water cooler, a $220 Motherboard and populating all 4 DIMM slots. This processor will likely have me reevaluating what I do with this system as the x79 platform is more robust than the Z68.

Perhaps I will change my mind again after I see what Ivy Bridge brings to the table though.

Excellent review Ryan, and I have to agree with Prodeous both about the charts and the continued excellence.



January 4, 2012 | 08:58 PM - Posted by Anonymous Coward (not verified)

The high end SB-E processors are enough of a shitty value themselves, but this takes the cake. You'd have to be a grade A moron to buy this over something like a 2600K or 2700K. Either you have the money to blow on a 6core SB-E, or you don't. This in between bullshit gets you SB performance and SB-E prices.

January 4, 2012 | 09:58 PM - Posted by iczerjones (not verified)

...with twice the memory bandwidth and more PCIe. It definitely fills a specific niche, but I'm not sure I would heckle a potential buyer as a 'moron'.

February 10, 2012 | 04:10 PM - Posted by Kilobit (not verified)

Umm only an uneducated idiot would say that. On a 2600k 0r 2700k your pci-e lanes have limited frequencies due to the very mild on chip intergrated graphics. I'll explain this in layman's terms... If you want to run multiple video/graphics cards your pci-e multipliers are limited to 8x/8x or 16x/4x if you use the SB-E chips without intergrated graphics you will be able to run 2 video/graphics cards @16x each and a third card @8x.Plus the SB-E chips fully support Pci-e 3.0 although regular SB chips are able to run pci-e 3.0 they do not fully support pci-e 3.0 because 3.0 came out much later than the release of the SB chips therefore they were not designed to run it.

January 5, 2012 | 08:16 AM - Posted by Robert Johnson (not verified)

Good review. I just wish Intel would release this CPU before February

January 5, 2012 | 11:10 AM - Posted by Octavean (not verified)

Excellent review and quite the feather in the cap of Pcper as you are one of the few to review all three Sandy Bridge-E processors. In fact I know of no other at this time that has. Most so far have only reviewed the Core i7 3960X. I think Anandtech only has a review of the 3960X and now the 3820 too.

Personally I was waiting for C2 stepping but the Core i7 3820 looks to be quite reasonable once its released. I still feel like X79 motherboards are missing features though. I’d like to see an updated chipset that has the features we were expecting out of the X79 (12 Intel SATA ports 3G + 6G, native Intel SRT and so on).

January 5, 2012 | 11:42 AM - Posted by Anonymous (not verified)

The biggest issue for me with this chip is the TPD. 130w vs. 95w makes this a no go for me. The minimal gains vs. the 2600k are not woth the added power consumption, especially when overclocked.

January 5, 2012 | 07:22 PM - Posted by tellis006

This was a great review, I also have a question, I have a 990X,GTX480,GI Assassin Mobo, with GB revodrive, while my rig is not quite a year old it is fast, the fastest I've ever had do you think I would benefit from a upgrade or should I wait till the next round. I have moved up the ladder selling and buying so I can have a nice rig. I have almost a thousand movies and tens of thousands of songs and use my computer for encoding mostly and play skyrim and COD4, and BF3 ?

January 6, 2012 | 11:01 AM - Posted by perfectshot (not verified)

Awesome! Can't wait to leave the Core 2 Duo era. Sure, I've got a quad now but the rest of the PC will be five years in March.

I wonder what difference the RAM speeds will make (1600 vs 1333)... Photomatix doesn't rely on CPU power as much as memory speed.

January 6, 2012 | 11:08 AM - Posted by cipher_nemo (not verified)

Just an FYI: your pricing column lists "(1k USD)", which should obviously be just "(USD)".

January 6, 2012 | 12:08 PM - Posted by superxero (not verified)

I imagine a lot of people who are considering the 3820 are currently running i7 920 rigs. Could you add the 920 to the benchmarks for comparison? It might be helpful to see whether the upgrade is worth it or not.

January 7, 2012 | 06:01 AM - Posted by rrr (not verified)

I don't think it's worth it over 2600k, unless you plan to go 3930k soon.

January 8, 2012 | 12:49 PM - Posted by Anonymous (not verified)

Am I missing something, but your charts show good metrics for
the Core i5 s, several times beating the i7's. What's the
answer? Channels? USB3? PCI?

January 17, 2012 | 12:27 PM - Posted by Eldonko (not verified)

SLI tests? Would have been nice to see the difference between 3820 and 2600k w/ multi-GPU.

February 1, 2012 | 06:22 AM - Posted by Anonymous (not verified)

In Romania is listed as "available for purchase" online at PcGarage.Price is exactly 300 euros.

November 16, 2012 | 11:56 AM - Posted by Anonymous (not verified)

the Core i5 s, several times beating the i7's. What's the

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