Overclocking

Sandy Bridge brought the motherboard's clock generator onto the 6-series chipset die. In doing so, Intel also locked its operation to 100MHz. While there was a bit of wiggle room, when combined with a locked processor, Intel effectively killed overclocking with most lower end Sandy Bridge chips.

For its more expensive CPUs, Intel offered either partially or fully unlocked (K-series) CPUs. The bus clock was still fixed at 100MHz, but you could overclock your processor by increasing its clock multiplier just like you could in the early days of overclocking.

With Sandy Bridge E, overclocking changes a bit. The clock generator is still mostly impervious to significant bus clock changes, however you're now able to send a multiple of its frequency to the CPU if you so desire. The options available are 100MHz, 125MHz, 166MHz and 250MHz.

Once again, wiggle room at any of these frequencies is limited so don't think we've moved back to the days of bus overclocking. You do get a little more flexibility, particularly with partially unlocked CPUs, but otherwise SNB-E overclocking is hardly any different from its predecessor.

Note that even if you select any of these options, the rest of the system still operates within spec. The multiplied bus clock is only fed to the CPU.

With a bit of effort I had no problems hitting 4.6GHz on my Core i7 3960X review sample. I had to increase core voltage from 1.104V to 1.44V, but the system was stable. While I could get into Windows at 4.8GHz and run a few benchmarks, the system wasn't completely stable.

No Cooler Included

None of the retail or OEM SNB-E parts include an Intel cooler in the bundle, a significant departure from previous CPUs. Presumably the cost of bundling a beefy cooler with these parts would've driven prices higher than Intel would've liked (remember you are getting a much larger die for roughly the same price as the outgoing Core i7 990X). Intel can also rationalize its decision against including any sort of cooler in the retail box by looking at the fact that many enthusiasts at this level opt for aftermarket cooling regardless.

Intel hasn't completely left SNB-E cooling up to 3rd party vendors however. There are two official Intel coolers available for use with SNB-E. The first is a < $20 heatsink that looks a lot like Intel's current coolers but with a couple of modifications (clear fan/shroud, retention screws instead of pegs). Intel states that this cooler is designed for operation within spec, meaning it could possibly limit overclocking attempts.

If you want an Intel branded overclocking solution, there's the RTS2011LC:

This is a closed loop liquid cooling solution similar to what AMD introduced alongside its Bulldozer CPU and similar to what many 3rd party cooling companies already offer. Intel expects its liquid cooling solution to be priced somewhere in the $85 - $100 range.

These closed loop liquid coolers are great primarily for getting away from the tower-of-metal heatsinks that have grown in popularity over the past several years. The radiator is a too small to compete with more traditional water cooling systems, but it can be a good gateway drug for the risk averse.

The Pros and Cons Cache and Memory Bandwidth Performance
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  • jabber - Monday, November 14, 2011 - link

    ...with Pixar updating their rendering farm?

    I cant think of many other big customers for this kind of chip.
    Reply
  • randinspace - Monday, November 14, 2011 - link

    Wouldn't they be using Xeons? Reply
  • gevorg - Monday, November 14, 2011 - link

    Could the wasted space for 2 fused cores and their L3 cache been used for HD2000 graphics? Wish Intel would have avoided wasting die space like this. Reply
  • GL1zdA - Monday, November 14, 2011 - link

    It's not wasting, it's binning. They could either throw away 8-cores with damaged cores or sell them as six-cores, which is what they did. Reply
  • BSMonitor - Monday, November 14, 2011 - link

    Actually it's not binning in this case. (some chips from the Xeon line might be) But these "desktop" CPUs are actually the 8-core Xeon line trimmed down in both cost and validation for use in Desktop PCs. Intel's currently roadmap is 6-core desktop CPU's at the high-end with extremely high memory bandwidth.

    It is cheaper for them to fuse two cores from an 8-core Xeon production line, than to redesign another CPU die for just the high-end 6-core desktop line. This class is by no means high-volume, hence yet another CPU die would be expensive.
    Reply
  • GL1zdA - Monday, November 14, 2011 - link

    Could you test how Sandy Bridge-E behaves in vt_benchmark when GPU trancoding is used? I'm curious, if SBE will do better than a nVidia 580. And what is the difference between 2600K+580 and 3960X+580 when GPU transcoding is enabled. Reply
  • Kevin G - Monday, November 14, 2011 - link

    Intel crippled both the CPU and the chipset with this launch. I was hoping to see an 8 core model at the high end. The chip design itself is an 8 core die so why not a fully functional chip for the low volume extreme edition? The performance benefits of the Core i7 3960X over the 990X mirror those from the 2600K over the 875K. (Well actually the 2600K vs. 875K comparison is much wider due to the clock speed differences, not just the architectural changes.) Sure it is faster at stock but generally not worth upgrading to, especially factoring in motherboard cost. Another let down is that the chip doesn't officially support PCI-E 3.0 True that their are no PCI-E 3.0 cards on the market today but there will be tomorrow. Not sure if this is additional crippling to distinguish the consumer chips from the coming LGA2011 Xeons or if there actually was a problem running at PCI-E 3.0 speeds.

    Speaking of Xeons, this article didn't mention if the system has the two QPI links disabled. If not, there could be the remote chance of a manufacturer releasing a board with the X79 using DMI and an X58 chipset hanging off of a QPI link. That would allow for another two full bandwidth PCI-E 16X slots at 2.0 speeds without the usage of a bridge chip.

    Then there is the X79 chipset. The reality is that it offers very little over the Z68. No USB 3.0 or additional SATA ports are the big things. Knowing Intel, we'll likely see a Z79 chipset that'll enable the SAS functionality for those that want more storage. Hopefully the hypothetical Z79 chipset will also use some of the PCI-E lanes from the CPU for additional bandwidth as an array of SSD's would easily be able to saturate the current DMI link.

    I'm also curious if these X79 consumer boards will allow for some overclocking with an LGA 2011 Xeon. I'm not expected full multiplier controller but rather feeding that 125 Mhz or 166 Mhz base clock to the CPU would suffice. Getting one of these consumer boards and paying the Xeon premium may wind up being the way to go for a true leap over of the Core i7 990X.
    Reply
  • khanov - Monday, November 14, 2011 - link

    Could the wasted space for 2 fused cores and their L3 cache been used for HD2000 graphics? Wish Intel would have avoided wasting die space like this.


    This is a good question, I guess many would wonder why this is the case. To understand why requires a little insight into the manufacturing of silicon chips:

    As with almost any manufacturing process there are variables that differentiate one product coming off the same assembly line from the next. So for example at a car factory each 'identical' engine is in fact a little different from another, whether it be the balancing of the crankshaft or the exact fit of the bearings.

    With the manufacturing of CPUs (and indeed any silicon chips) there are also small differences between the chips that come off the same assembly line. If a chip has a defect for example (which happens too frequently) the defective area of the chip needs to be disabled. In essence this is why we are seeing Sandy Bridge-E cpus launching with disabled cores.

    The fully enabled cores (eight cores and 20MB L3 cache) are being sold as (or will soon be sold as) Xeon chips for the highest price. Somewhat lesser cores with defects are being sold as lower end Xeons with six cores or as consumer Sandy Bridge-E chips with six cores. Even more defective chips that can only work with four cores enabled are being stockpiled and will soon be sold as four core Sandy-Bridge-E and Xeon chips.

    So basically all these chips are manufactured with eight 'possible' cores. There is no wasted space on the die. However due to imperfect manufacturing processes some of these chips will have defects. In fact the larger the die area the more likely a defect occurs within each chip. With a very large die area for SB-E intel is now experiencing a problem more often seen by GPU manufacturers such as Nvidia. They are dealing with the problem in the same way: While Nvidia sell a GTX580 with die defects as a GXT570, intel sells a defective 8 core SB-E as a fully working 6 core Xeon or SB-E chip.

    Once we see an improvement of the manufacturing process (which is an ongoing process of improvement) we will start to see lower cost SB-E chips and also possibly fully enabled, defect-free SB-E for desktop/workstation users.
    Reply
  • javalino - Monday, November 14, 2011 - link

    AGREE!!!!I will wait for a native 6 core, it will be much cooler , and maybe 1% faster Reply
  • karakarga - Monday, November 14, 2011 - link

    Hi,
    From i386 DX-40 times, AMD build it's worst CPU ever. With 2 Billion transistors, instead of 0,9 Billion transistors. Typically new Bulldozer architecture have not much effect. So they doubled the transistor count for nothing! A very poor design. I am thinking AMD FX-8150 is not an eight core but considering new AMD bullozer 8C CPU as a 4 core but 8 threaded. Intel here reached 2,3 Billion transistors. But the performance is about 1,5 times better than AMD.

    Chipset details are known. The lack of having only two SATA-600 ports is a disadvantage. Lack of native USB 3.0 support prevents mainboards fully passing to the new speed standard.

    But AMD is also not good at chipset design too. I am currently using 990FX chipset with 1090T cpu. The memory performance is not reaching to 10GB/s with four DDR3-2133 rams working at 1600MHz default. If I put this CPU on a 790FX mainboard with only two piece DDR2-1066 rams, it passes 13GB/s. Which means the old serie upto 1100T are designed for DDR2 and not poolished and optimized fine for DDR3 memory. Only advantage here is having 6 SATA-600 ports, thats all!
    Reply

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