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.



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


View All Comments

  • - Thursday, March 11, 2010 - link

    how are you getting your productivity numbers/percentages ??? Reply
  • Anand Lal Shimpi - Thursday, March 11, 2010 - link

    Also note that I limited my voltage to a ~15% increase. I believe with more voltage it's possible to go higher, but you really start driving power consumption up at that point.

    Take care,
  • zartok - Thursday, March 11, 2010 - link

    I saw on tweakers.net they were able to run it 3.45GHz on 1V and on 4.26GHz on 1.38V (or 1.33V can't tell that well due to the image size), without even trying hard. So are sure that it's the CPU that's limiting the OC and not something else eg the motherboard? Reply
  • Bolas - Thursday, March 11, 2010 - link

    How does this cpu compare to the 6-core 32nm Xeon server chips that are launching around the same time? Any cost information on those yet? I mention this because I'm seriously considering EVGA's new dual socket W555 motherboard, which requires the dual QPI cpu's. Reply
  • goinginstyle - Thursday, March 11, 2010 - link

    Is Intel offering 18 months no interest no payment plans for this? I really want one but I also want to eat and live in something besides a box for the next six months. Good article and nice to know the X58 boards we already have should work with nothing more than a BIOS upgrade. Reply
  • JonnyDough - Thursday, March 11, 2010 - link

    This processor isn't for you then.

    It's for people who have nothing better to blow money on AND have money.
  • DrMrLordX - Thursday, March 11, 2010 - link

    This is mostly a paper launch since few people will pay $1k for a CPU. As has been said so many times in the CPU/OC forums, keep your eyes out for the 32nm Xeon quads that will be appearing for LGA1366. They won't be 920 d0 cheap but they will be cheaper than the 980 and probably OC pretty well.

  • erwos - Thursday, March 11, 2010 - link

    If it's in the channel, it's not a paper launch. Period, end of story. Just because you can't afford it doesn't mean others can't. Reply
  • DrMrLordX - Friday, March 12, 2010 - link

    It's not that it's unaffordable . . . it's just that I'm not that crazy. Close, but not quite. Reply
  • JumpingJack - Friday, March 12, 2010 - link

    Maybe a career change that pays more :) ... j/k. Reply

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