A 12MB L3 Cache: 50% Larger, 14% Higher Latency

Gulftown sticks to Ronak’s 2MB of L3 per core rule and has a full, 12MB shared L3 cache that’s accessible by any or all of the six cores. It’s actually because of the large unified L3 cache that performance in applications that don’t use all six cores can be higher than quad-core Core i7s.


Nehalem


Gulftown

The added cache does come at the expense of higher access latency. Nehalem and Lynnfield had a 42-cycle 8MB L3, Gulftown has a 48 cycle 12MB L3. A 14% higher latency for a 50% increase in size. Not an insignificant penalty, but a tradeoff that makes sense.

Identical Power Consumption to the Core i7 975

Raja has been busy with his DC clamp meter measuring actual power consumption of CPUs themselves rather than measuring power consumption at the wall. The results below compare the actual power draw of the 32nm Core i7 980X to the 45nm Core i7 975. These values are just the CPU itself, the rest of the system is completely removed from the equation:

CPU Intel Core i7 980X Intel Core i7 975
Idle 6.3W 6.3W
Load 136.8W 133.2W

 

Thanks to power gating, both of these chips idle at 6.3W. That's ridiculous for a 1.17B transistor chip. Under full load, the two are virtually identical - both drawing around 136W.

Westmere Goodness

The Core i7 980X is the first LGA-1366 processor based on Intel’s Westmere architecture, but unlike Clarkdale it does not have an on-die PCIe controller or on-package graphics. If anything, Gulftown really looks like a 6-core, 32nm version of Bloomfield rather than a scaled up Clarkdale. The similarities to Bloomfield extend all the way to the memory controller. Gulftown only officially supports three channels of DDR3-1066 memory, not 1333MHz like Lynnfield or Clarkdale. Of course running DDR3-1333 memory is possible, but the memory controller is technically operating out of spec at that frequency.

The processor does retain the Westmere specific features. The first Core i7 did not power gate its L3 cache, Lynnfield added it and Gulftown has it as well. While Mainly improved power efficiency and AES-NI instructions. I looked at the performance improvement offered by AES-NI acceleration in our Clarkdale review. If you use BitLocker or do a lot of archive encryption/decryption, you'll appreciate Gulftown's AES-NI.

Index The Roadmap: Sandy Bridge in 2011
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  • JumpingJack - Monday, March 15, 2010 - link

    THG's power numbers are often screwed up, I would not trust them.

    Good sites for power numbers include this, TR, Xbitlabs, and lost circuits. I have never been able to come close to any of Tom's numbers even with identical HW.
    Reply
  • OBLAMA2009 - Friday, March 12, 2010 - link

    how come anand says he's excited about it and then later he says he'd never spend money on it

    personally i wouldnt spend that much on a cpu but i think this thing would be a good chip for so long that if you did it wouldnt be a bad deal even at 1000. itll probably be the close to the fastest chip for the two years
    Reply
  • Paladin1211 - Thursday, March 11, 2010 - link

    I can't figure out why the i7 870 only gets 70.6 fps in WoW while the i7 920 gets 85.5 fps. Higher clock, higher turbo, same hyper threading, integrated PCIe lanes... yet the 920 is 21% faster.

    Someone enlightens me please :(
    Reply
  • JumpingJack - Friday, March 12, 2010 - link

    That's a good question .... it shouldn't. Reply
  • p05esto - Thursday, March 11, 2010 - link

    I'm going through withdrawl. I've had my Core i7 920 since the day they were released and really want to upgrade, like yesterday. But I'm not spending $1k on a CPU, maybe $400 could work :) if they came out with something decent and overclockable to get near the extreme version. I feel like I'm stuck at the moment....I feel the need, the need for speed!!! Reply
  • bludragon - Thursday, March 11, 2010 - link

    Well it's a beast, no doubt about that. But the most interesting info here is that sandy bride is debuting as a mainstream part. Has this ever happened with a new cpu before? Is this just because they are going to start with less cores, or have they taken some other architectural departure? Reply
  • RamarC - Thursday, March 11, 2010 - link

    btw, i'm trademarking "sexycore" Reply
  • Lazlo Panaflex - Thursday, March 11, 2010 - link

    "I wonder where Intel will price the Core i7 970, allegedly also a 6-core Gulftown derivative"

    Hey Anand, if history is any indication, and there's no competition from AMD, I'll bet you a dollar that the 970 will retail for around $850 - the same price of the venerable mainstream Q6600 that was released a few months after the $999 QX6700... ;)
    Reply
  • aigomorla - Thursday, March 11, 2010 - link

    i heard it was gonna be near the 600 mark.

    It wont be cheaper then the 960, and it wont be more expensive then a 980X.

    Reply
  • Robear - Thursday, March 11, 2010 - link

    You start by saying, "I have to say that Intel's Core i7 980X is the first Extreme Edition CPU that I've ever gotten excited about. ... The 980X gives you its best regardless of what you throw at it. ... If money were no object, the Core i7 980X is clearly the best you can get."

    But then you conclude with a much more somber, "The Core i7 980X is such a difficult processor to recommend."

    What really threw me for a loop, though, was this comment: "You could pick up a dual-socket Xeon board and a pair of quad-core Nehalem Xeons for a bit more than a X58 + 980X"

    There are so many problems with that statement :( It's very un-anand-like.

    Foregoing any assumptions about what you mean specifically, I haven't seen any 3.0+ GHz XEONs sub $1,000. Even then, I'm not convinced a dual-quad would even outperform the 980 unless you went with a couple of EPs, and that's way off the price mark. Your conclusion ends with a mild suggestion towards a platform you didn't benchmark. The 980 can put you at 3.6 GHz in a single-threaded app which you can't get from a dual-XEON.

    The 980 truly is the best of both worlds, as you initially indicated.

    Given that that the 960 is 3.2 GHz @ 4 cores is running ~$600, you can snag a whole 2 more cores, a speed boost, AND other 980-only perks for an extra $400. Think back to what the EE got you at its debut - another 10%-20% clock and an unlocked multiplier for something like a 100% markup over the next highest model.

    This chip really seems like a bargain, but that's my opinion. I'm considering the 980X over a new 930 build just for the longevity it provides. It's just SO much power for the money. The simple fact that it puts it in the same league as a dual-quad XEON raises the hair on the back of my neck :)

    Can you elaborate on a XEON system that would be comparable in performance and price to the 980? Maybe that would be a good article. I wonder what kind of performance hit you take with the QPI between two chips versus what you get with the 980. Skilltrail did okay, but the FB-DIMMs really hurt gaming. I think a 980 v. XEON would be a great article.
    Reply

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