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CrossFire And SLI: Power Consumption And Noise

AMD Radeon HD 7950 Review: Up Against GeForce GTX 580
By

Power

Oddly, two Radeon HD 7970s use just slightly less power at idle than two Radeon HD 7950s. The point is, however, that they both draw a lot less than any other combination of cards.

And just look at those two GeForce GTX 590s sitting there, slurping down a whopping 84 W more than the 7970s on Windows' desktop!

If you flip back and forth between this page and the previous one, you'll notice that each 7900-series CrossFire setup is only using around the same amount of idle power as a single-card arrangement. That’s because they’re doing this:

That’s one card idling (in the back), its PCI Express 3.0 link throttling to 1.1 transfer rates to cut power, as the other card (up front) completely spins down.

As a result, you get even more impressive power results when output is cut to the attached display. The Radeon HD 7950 and 7970 CrossFire configs each shed an additional 6 W of consumption.

For their ability to deliver the fastest Metro 2033 results in CrossFire, beating quad-GPU Radeon HD 6990 and GeForce GTX 590 configurations, the Radeon HD 7970 and 7950 are also the two most power-friendly choices cards you could put together in multi-GPU arrangements.

And that’s under load. We’ve already seen how much better they are at idle. If you were to calculate out the efficiency of these cards versus older AMD and Nvidia boards, they’d almost certainly stomp everything else out there. Performance per watt is where it’s at.

Noise

The Radeon HD 7900s again show well when it comes to keeping idle acoustic output to a minimum. Nvidia’s cards are similarly silent. And although the Radeon HD 6990s come in last place, they’re still hardly a distraction.

As long as you have a full expansion slot separating two dual-GPU cards, the noise generated by a CrossFire or SLI configuration isn’t markedly higher than one board operating on its own in the real-world gaming environment we’re testing.

AMD is using a centrifugal fan design that exhausts all of its heated air, which we applaud.

The only odd result here is the Radeon HD 6990s, which operate more quietly in a quad-CrossFire arrangement than one card flying solo. Fortunately, the explanation is pretty simple. Compared to two GeForce GTX 590s, which are fully taxed in Metro 2033, the 6990s hover between 60 and 80% GPU utilization according to GPU-Z.

Our presumption is that host overhead is higher, so we’re seeing a bottleneck that inhibits performance, which would explain why one 6990 was able to outmaneuver a 7970 at 2560x1600, but even two 7950s beat a pair of 6990s at the same resolution.

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Top Comments
  • 26 Hide
    bak0n , January 31, 2012 3:38 AM
    More good GPU news. Keep em coming!
  • 24 Hide
    hardcore_gamer , January 31, 2012 4:29 AM
    According to W1zzard's review, this card tops the Performance / Watt chart.
  • 22 Hide
    Anonymous , January 31, 2012 4:24 AM
    It beats the GTX580 one on one in most benchies and that's not taking into account the overclocking headroom these things have, they're also power friendlier and with XFX, cooler, quieter and expected to be cheaper so what's the problem? Me thinks me smell's NV fanboys!!
Other Comments
  • 26 Hide
    bak0n , January 31, 2012 3:38 AM
    More good GPU news. Keep em coming!
  • 21 Hide
    thesnappyfingers , January 31, 2012 4:02 AM
    stm I was thinking the same thing. But then agian it is still cheaper, more efficient compared to the gtx 580. Still, I am waiting it out till kepler.
  • 8 Hide
    Derbixrace , January 31, 2012 4:19 AM
    great value compared to the 7970 because you can OC it to be faster than it on stock voltage and even further with voltage tweaking ;) 
  • 6 Hide
    esrever , January 31, 2012 4:23 AM
    I'd love to have one once kepler comes and these drop in price. Im gonna start saving.
  • 22 Hide
    Anonymous , January 31, 2012 4:24 AM
    It beats the GTX580 one on one in most benchies and that's not taking into account the overclocking headroom these things have, they're also power friendlier and with XFX, cooler, quieter and expected to be cheaper so what's the problem? Me thinks me smell's NV fanboys!!
  • 24 Hide
    hardcore_gamer , January 31, 2012 4:29 AM
    According to W1zzard's review, this card tops the Performance / Watt chart.
  • 3 Hide
    primonatron , January 31, 2012 4:29 AM
    Are the Skyrim benchmarks on the v1.4 beta patch?

  • 9 Hide
    dragonsqrrl , January 31, 2012 4:29 AM
    rmpumper7950/7970 should be priced ~$50+ of 6950/6970 prices. So as it is now, if nvidia's gtx680 will be better than 7970 they will price it at >$600? That's a load of crock.

    Every rumor and leak I've seen so far on gk104 pricing seems to indicate otherwise...

    http://www.guru3d.com/news/nvidia-gk104-kepler-gpu-priced-at-299-230-/

    According to Nvidia's AIB partners the initial price set for the first gk104 based graphics card is $300. Of course this can go up or down based on the competition. Unfortunately, I have the feeling it'll be going up.
  • 3 Hide
    giovanni86 , January 31, 2012 4:43 AM
    This is all good news for the GPU market and for fans of ATI. Waiting on keplar from Nvidia, i buy into the marketing of "The way its meant to be played" =D hahahah. But great news, i love seeing my card get rocked. Competition is always great for pricing =D
  • -7 Hide
    msgun98 , January 31, 2012 4:52 AM
    lou007aIt beats the GTX580 one on one in most benchies and that's not taking into account the overclocking headroom these things have, they're also power friendlier and with XFX, cooler, quieter and expected to be cheaper so what's the problem? Me thinks me smell's NV fanboys!!


    Congratulations. The 7950 narrowly beats a year old card and costs the exact same. No thanks, I'll wait on Kepler and then decide what to get once AMD puts down the pipe and has to get real on their prices. And I'm a proud owner of a 4870.
  • 1 Hide
    giovanni86 , January 31, 2012 5:04 AM
    lou007aIt beats the GTX580 one on one in most benchies and that's not taking into account the overclocking headroom these things have, they're also power friendlier and with XFX, cooler, quieter and expected to be cheaper so what's the problem? Me thinks me smell's NV fanboys!!


    It does beat it, i can say it does.. My SC GTX580 was pulling around the same bandwidth as one they have here, i overclocked it and was getting almost 200GB's of bandwidth and was quite surprised i was able to push it and keep it like that with no trouble at all in any game i play and pretty much passed each stress test without any artifacts that i ran for hours. Headroom to OC differentiates from card to card, and nothing is guaranteed. But of course with 7950 im impressed it does very well even though the spec's on it look like it can run a marathon around the 580 with no trouble at all, but it does keep up with it and battle it out. I hope nvidia see's this as a threat and drops there price on the 580 so i can pick up another for around $400 =D Would make me very happy.
  • -1 Hide
    de5_Roy , January 31, 2012 5:22 AM
    nice.
    7950's power consumption in single and cfx mode are quite impressive.
    i'll compare them to kepler when they come out and get tested.. right now, gcn high end looks much better than fermi high end (gpu compute, power efficiency etc).
    amd's driver support seems inconsistent as usual... hopefully more mature drivers will bring out even more performance out of the gcn cards.
  • 4 Hide
    kvarta , January 31, 2012 5:23 AM
    That's strange, in other sites says that card is "...relatively inaudible...". Example:
    http://www.guru3d.com/article/his-radeon-hd-7950-review/25
    As always good job Chris.
  • -2 Hide
    dragonsqrrl , January 31, 2012 5:45 AM
    kvartaThat's strange, in other sites says that card is "...relatively inaudible...". Example:http://www.guru3d.com/article/his- [...] -review/25As always good job Chris.

    The editors at Guru3D perform their noise tests differently than most other sites. The cards are placed in a closed case and measurements are taken from a few feet back. These editors are also either partially deaf, or they just don't give a damn about excessive system noise. Honestly, I don't think they've ever knocked a card for being too loud, even the HD6990.
  • 13 Hide
    tlmck , January 31, 2012 5:55 AM
    Bring on the mid range!
  • 10 Hide
    jezus53 , January 31, 2012 6:07 AM
    msgun98Congratulations. The 7950 narrowly beats a year old card and costs the exact same. No thanks, I'll wait on Kepler and then decide what to get once AMD puts down the pipe and has to get real on their prices. And I'm a proud owner of a 4870.


    You are aware that the 7950 is not supposed to directly compete with the 580, right? The 7970 is supposed to beat the 580 and the 7950 is supposed to beat the 570. Just like how the 6970 is supposed to compete with the 580 and the 6950 is supposed to compete with the 570. The shear fact that the non flagship GPU beats the flagship GPU of your competitor is pretty awesome.
  • 5 Hide
    lordstormdragon , January 31, 2012 6:15 AM
    jezus53The shear fact that the non flagship GPU beats the flagship GPU of your competitor is pretty awesome.


    AMD has had plenty of time to play catch-up. It's not "pretty awesome" they leap-frogged Nvidia once again. It's a calculated move on AMD's part, for certain. A good one, but "pretty awesome" is very far from "standard dual-monopoly leap-frogging that's gone on since both companies started". Relax.

    That said, I DO celebrate and find it ironic that AMDs 7950 is as flag-shippy whoop-ass as Nvidia's 7950 was in its day! I'm looking at my dead beast here right now. Miss you, 7950GT. I... I loved you. I can say that, now.


  • 4 Hide
    stm1185 , January 31, 2012 6:22 AM
    jezus53You are aware that the 7950 is not supposed to directly compete with the 580, right? The 7970 is supposed to beat the 580 and the 7950 is supposed to beat the 570. Just like how the 6970 is supposed to compete with the 580 and the 6950 is supposed to compete with the 570. The shear fact that the non flagship GPU beats the flagship GPU of your competitor is pretty awesome.


    It is not pretty awesome that your next gen part that you priced slightly below the competitors flagship last gen part outperforms it in some tests. That is to be excepted. The 7950 is not against a gtx 570, its against a gtx670 which is not out yet, and will probably be replaced around the same price point as a 570 with a large performance increase over it, making buying a $450 7950 retarded; as such the 7950 will then get dropped to where the 6950 is now to be competitive.

    Anyone who buys a 7950 before AMD at $450 is a chump. 30%+ price drop as soon as Nvidia releases its next gen.
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