The article says it all: for simple code AMD gives you more bang for the buck. However, GPU-Grid does not fit into this category (as far as I see it).

They already built an AMD app.. however, performance was quite bad (on VLIW chips, no GCN yet). And it wasn't stable due to bugs in the driver or SDK. In short: they're trying to support AMDs, but it's not as easy as the article might make one to believe.

MrS

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Scanning for our furry friends since Jan 2002

Hi, What I find is that AMD inmegable is getting the batteries. Greetings.

http://blogs.amd.com/developer/2012/05/21/opencl%E2%84%A2-1-2-and-c-static-kernel-language-now-available/

Hi, What I find is that AMD inmegable is getting the batteries.

Is that a machine translation? Sorry, I can't figure out any sense in this sentence.

MrS

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Scanning for our furry friends since Jan 2002

Hi, What I find is that AMD inmegable is getting the batteries.

Is that a machine translation? Sorry, I can't figure out any sense in this sentence.

MrS

Hi, I'm sorry, I mean that AMD is getting better and pushing Nvidia. Greetings.

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http://stats.free-dc.org/cpidtagb.php?cpid=b4bdc04dfe39b1028b9c5d6fef3082b8&theme=9&cols=1

BTW looking at the GK110 architecture, I can see that it is superscalar (in single precision) as well as the GK104, so only 960 of its 2880 shaders could be utilized by GPUGrid.

Isn't that "1920 out of 2880"? Assuming the superscalar capabilities can still not be used (newer architecture, newer software.. not sure this still holds true for Kepler).

MrS

Looking at the performance of the beta workunits, I came to the conclusion that Kepler can utilize only 1/3rd of it's shaders.

You're referring to this post? If so (I don't want to read the entire thread now, it's quite long and the forum says I haven't read it yet) .. you forgot an important factor of 2!

GTX680 is 150ns/115ns = 1.30434 times faster than GTX580. It's got 3 times as many shaders, so we might have expected a performance increase by a factor of 3. That would be 1.3/3 = 43% shader utilization by now. However, GTX580 runs its core at 772 MHz and its shaders at 1544 MHz. GTX680 runs the shaders at 1006 MHz, so we should actually expect a performance increase of 3*1006/1544 = 1.95. So the shader utilization on Kepler appears to be 1.3/1.95 = 66.5%.

That's 2/3 rather than 1/3 and fits the assumption very well that the super scalar capability can still not be used by GPU-Grid, despite the changes nVidia made to the compiler and scheduling (which was actually meant to save power, not increase performance).

BTW: the lower clock speeds of Kepler chips are key to its power efficiency.

MrS

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Scanning for our furry friends since Jan 2002

I got your point.
I assumed that nVidia redesigned their shaders in a way that the shaders of the Kepler chip can do as much work as the shaders of the Fermi can do at doubled clock speed (to compensate the eliminated hot clocks). Apparently I wasn't right about it. (they put 3 times as much shaders to compensate the lack of hot clocks)
My 'reviewed' conclusion is that while it can utilize 2/3rd of its shaders, the Kepler performs as if it could utilize only the 1/3rd of its shaders, because of the eliminated hot clocks. On the other hand it's much more power efficient for the same reason.
Scaling the (theoretical) performance indices of the Kepler (GK104) and the Fermi (GF110) looks like:
(1536*2/3*1006)/(512*772*2)=1.3031
Apparently we get the same result, if we take out the "*2" from both performance indices at the same time:
(1536/3*1006)/(512*772)=1.3031

BTW: the lower clock speeds of Kepler chips are key to its power efficiency.

Yes, it's the key for every chip. That's why Intel couldn't reach 10GHz with Pentium 4, as it was planned when the netburst architecture was introduced.

I wonder how much overclock the Kepler could take?

Depends on the chip. But not alot. 1300 seems to be about the limit. At this point, the locked voltage becomes an issue. However, realistically most are seeing 1200-1250.

My 680 can go up to about 1275, but I tend to keep it at 1200 w/ +100 memory (3100)

With a flashed BIOS and extreme cooling. They're getting into "hot clock" territory. Around 1400+

Won't be until next year that we see the full potential of the Keplers, in any format.
Looking forward to seeing a full-fat Kepler, or at least the results. I'm not saving for one however.

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My 'reviewed' conclusion is that while it can utilize 2/3rd of its shaders, the Kepler performs as if it could utilize only the 1/3rd of its shaders, because of the eliminated hot clocks. On the other hand it's much more power efficient for the same reason.

While we're talking about the same numbers, I prefer to use the "real" clock speed and say "2/3 of the shaders", as this corresponds directly to not being able to use the super scalar ones. This is more straight forward and easier to understand. Saying "can use only 1/3 of its shaders" makes it seem like a really really bad design - which it isn't.

MrS

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Scanning for our furry friends since Jan 2002