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Compute Performance

Moving on from our look at gaming performance, we have our customary look at compute performance. Since compute performance is by definition shader bound, the 7950 is at a bit of a disadvantage here compared to gaming performance. Whereas ROP performance scales with the core clock, shader performance is hit by both the reduction in the core clock and the disabled CU array.

Our first compute benchmark comes from Civilization V, which uses DirectCompute to decompress textures on the fly. Civ V includes a sub-benchmark that exclusively tests the speed of their texture decompression algorithm by repeatedly decompressing the textures required for one of the game’s leader scenes. Note that this is a DX11 DirectCompute benchmark.

AMD’s greatly improved compute performance continues to shine here, though in the case of Civilization V it’s largely consumed by just closing the previously large gap between the GTX 500 series and the Radeon HD 6000 series. As a result the 7950 falls ever so short of the GTX 580, while the factory overclocked Sapphire and XFX cards give the 7950 enough of a push to come within 5% of the 7970.

Our next benchmark is SmallLuxGPU, the GPU ray tracing branch of the open source LuxRender renderer. We’re now using a development build from the version 2.0 branch, and we’ve moved on to a more complex scene that hopefully will provide a greater challenge to our GPUs.

Under SmallLuxGPU the 7970 enjoyed a large lead over the GTX 580, and this continues with the 7950. Even though the 7950 is well behind the 7970—to the tune of 24%—it’s still 33% ahead of the GTX 580 and the lead only grows from there. Meanwhile the XFX and Sapphire cards can catch up to the 7970 somewhat, but as this is truly a shader-bound test, you can’t make up for the lack of shaders units on the 7950.

For our next benchmark we’re looking at AESEncryptDecrypt, an OpenCL AES encryption routine that AES encrypts/decrypts an 8K x 8K pixel square image file. The results of this benchmark are the average time to encrypt the image over a number of iterations of the AES cypher.

In spite of being a compute benchmark, AESEncryptDecrypt is not particularly sensitive to GPU performance, showcasing the impact that setup times can have. The 7950 trails the 7970 by 10%, and overclocking doesn’t change this much. Unfortunately for AMD NVIDIA is still the leader here, showing that AMD’s compute performance still has room to grow.

Finally, our last benchmark is once again looking at compute shader performance, this time through the Fluid simulation sample in the DirectX SDK. This program simulates the motion and interactions of a 16k particle fluid using a compute shader, with a choice of several different algorithms. In this case we’re using an (O)n^2 nearest neighbor method that is optimized by using shared memory to cache data.

With the compute shader fluid simulation we once again shift back into a compute task that’s much more shader-bound. The 7950 only reaches 80% of the performance of the 7970, once more proving the real impact of losing a CU array. This is still enough to handily surpass the GTX 580 however, with the 7950 taking a 15% lead.

Civilization V Power, Temperature, & Noise
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  • Galidou - Sunday, February 05, 2012 - link

    Oh wait, wait, the 9800gx2 was priced 150$ lower than the GTX 280 and was performing more than gtx 280!! LOL speak about mispricing.... LOL OMG THAT'S RIDICULOUS Reply
  • Galidou - Sunday, February 05, 2012 - link

    LOL that 7970 story pricing like it was the worst decision a Video card manufacturer ever made is so ridiculous chizow, it'S not a good decision either, we would all like to see lower prices considering we know the size of the die under the hood and we know it can be priced lower.

    But that GTX 280 thingy because Nvidia was thinking they had no competition was a little like taking people for DUMMIES. The radeon 4870 wasn't so mispriced, it was the gtx 280 that WAS. The GTX was uber big but didn'T justify over triple the price of 8800gt or higher price than a 9800gx2 considering the performance of those parts..... HELL NO.

    In the end, I prefer a pricing according to performance than being taken for a DUMMY by a company leading the technology with a little more performance...
    Reply
  • chizow - Sunday, February 05, 2012 - link

    Like I said Galidou, the GTX 280 absolutely earned the original MSRP. It was a true flagship card in every respect and maintained the price:performance increase you would expect from a new next-gen GPU over its predecessor.

    You still haven't refuted this because again, the data is all out there. It was over 1.5x faster than the 8800GTX/9800GTX and roughly the same speed as the 9800GX2, the minimum baseline expectations anyone should have for a new flagship card on a new arch/gen/process.

    AMD was the one who mispriced their card at the time they could least afford to do so. Some like myself argued they just didn't know how to make money. They could've easily priced it at $400 and STILL forced Nvidia to drop prices on the GTX 280 and especially the GTX 260.

    But yes, Nvidia looked horrible after that decision but did right by their customers by issuing rebates. Now AMD is in the exact same position and stands to look badly with this pricing. Do you really think they will do the same if Nvidia forces them to cut prices on these parts? Its OK, you can say a bad thing about AMD too. ;)
    Reply
  • chizow - Sunday, February 05, 2012 - link

    We've already covered this, because with the exception of very rare and extraordinary increases like the 8800GTX or 9700pro, 2x increases over last-gen flagships are NOT normal.

    The GTX 280 was easily 2x faster than the 8800GT, but the 8800GT was a refresh mid-range performance product. Whatever price:performance discount it carried already existed compared to the high-end parts of the time like the 9800GTX and 9800GX2, where it cost significantly less for excellent performance.

    Similarly, in these last few generations of cards mid-range cards like the GTX 460 and GTX 560 can be had for less than half of what a GTX 480 or GTX 580 cost but they perform much better than the cost would indicate. Obviously the top Kepler does not need to be 3x faster than the GTX 560 in order to command a $500 price tag commensurate with the flagship slot.

    In summary, the top cards do command a premium and determine the pricing for all cards that follow, but their merit for commanding that top price is judged against previous cards and generations.

    Its already become obvious that 15-25% increase from Tahiti over Fermi doesn't carry enough mustard to push the stack, since its momentum wasn't enough to even shift the metric at the second stop, the 7950.
    Reply
  • Galidou - Sunday, February 05, 2012 - link

    It was the same performance than a 9800gx2 when it was in 2560* resolution because of memory, for the rest(99.5% of the people with 1080p or less back then) the 9800gx2 was truncating the gtx280 for 150$ less. Reply
  • chizow - Sunday, February 05, 2012 - link

    No it was trading blows with the 9800GX2 and beating it at the highest resolutions and AA settings that mattered for people looking to upgrade.

    This is going to happen with any new flagship part because of the overall increased pipeline. High-end cards are meant to push high-end settings and resolutions because what you have is usually enough at lower end settings. This is why we "upgrade".

    Regardless, X2 parts are always going to carry some performance advantage at cheaper prices but that's because single-GPU always carries a premium that goes with being the top single-GPU flagship.

    You can look at any forum and you see this decision making process all the time with both last-gen GPUs and newer ones.

    But back to the point. Flagship next-gen GPUs do generally tend to compete with last-gen X2 in performance, not always a convincing win across the board, but enough to effectively retire those cards. That's clearly not the case with the 7970.
    Reply
  • Galidou - Sunday, February 05, 2012 - link

    Nope you still can,T say something wrong about Nvidia you corrected them by saying they issued rebates to their customers, and AMD is not in the same position, they did not price it for dummies, it'S accordingly to it'S performance... wow when will you realize triple the price and according to it'S performance is different? that's all I wan you to say lol! Reply
  • chizow - Sunday, February 05, 2012 - link

    Is the 7970 triple the performance of the 6950? So then how does it justify 3x the price?

    Its amazing how you want to try to hold Nvidia to this flawed logic and dismiss it when the 7970 fails even WORST at meeting it.

    Again, this just makes you look incredibly stupid or incredibly dishonest, neither of which are flattering.
    Reply
  • Galidou - Sunday, February 05, 2012 - link

    it'S not triple the price of 6950 it's a LITTLE more than double, fi you have to lie this discussion is over..... when I said triple the price of the 8800gt I was gentle, 650$ for gtx 280 while 8800gt were selling for I remember I got one for 180$ so that's in fact three times and a half, plus we're comparing a 1gb video card price to a 3gb while GTX 280 and 8800gt had 256mb difference.... Now that I see you have to lie I don't want to continue this, I may be not right in EVERYTHING I say but I ain't lying big time....

    I prefer to be honest in my opinion than being dishonest in a certitude.....

    Ati radeon 3870 sucked big time, they never offered as good a competition to Nvidia after the X1xxx products in my opinion and Nvidia have(most of the time) got better drivers, I prefer their interface, I dislike catalyst. Here's what I have to say about ATI and I have not much wrong about Nvidia but at least I can say I see both side of the medal.

    Good luck in the future, peace out.
    Reply
  • Galidou - Sunday, February 05, 2012 - link

    I was offering you my perception ok I played the troll but I never lacked respect to you, I'm not saying you are stupid or anything while you did, respect is something you can't buy.

    I may be poking your opinions because you see them as fact but thing is perception is different for everyone. I do not see anything SO wrong in the pricing of the 7970 while you obviously see something very bad in it. I can'T make you see my point of view so I guess you and I are right, depends for who reads us.

    respect.
    Reply

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