Retesting the Radeon HD 4830: Too Few SIMDs Enabled
by Derek Wilson on October 25, 2008 12:00 AM EST- Posted in
- GPUs
Performance Improvement with 8 SIMDs
The maximum theoretical performance difference between the two configurations is 14.3%. We re-ran our tests at 1680x1050 for all games but Crysis and Age of Conan which we re-ran at 1280x1024. We computed the percent increase between our previous data and the new numbers and plotted them on the following chart. To get a better sense of the significance of the performance increase, we set the maximum on the x-axis to 15 (to reflect the maximum performance increase we could possibly see).
We did re-run all of our numbers, but rather than reporting them all here, we have just updated our previous article with the corrected data. This shows that there was indeed an impact, but that it wasn't quite as large as the theoretical maximum. Because the only difference between this and the 4850 is clock speed an the number of SIMDs, this would indicate that there while more compute and texture hardware does improve performance, the performance of AMD hardware doesn't scale linearly with SPs. NVIDIA hardware does come closer to scaling linearly with SPs as we've seen in past tests (and as evidenced by the GTX 260 core 216), but the architecture is a bit different. It is possible that the bottleneck in the games we tested is just elsewhere and we would see more linear scaling on more shader intensive code.
In any case, while the increases are significant (in most cases), the impact on our conclusions isn't huge. It doesn't fundamentally change the class of the hardware.
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CEO Ballmer - Sunday, October 26, 2008 - link
You people need to give Vista a second chance too!http://fakesteveballmer.blogspot.com">http://fakesteveballmer.blogspot.com
JonnyDough - Sunday, October 26, 2008 - link
a button. My guess is that AMD did this intentionally to get more people talking about their card.Griswold - Sunday, October 26, 2008 - link
Oh yea, I'm sure the somewhat unfavorable comparisons to the 9800GT in a number of reviews because of this mishap will magically turn into an advantage too.Glad you're not responsible for any marketing at AMD - you'd proof that it *can* get worse. :P
MrSpadge - Sunday, October 26, 2008 - link
from what you're writing it's clear that the x-axis indicates "performance improvement in %", but it's not written there. Professional graphs need proper axis.RagingDragon - Saturday, October 25, 2008 - link
So will be seeing a 4810 with 480 or 560 SP's? That'd fit nicely in between the 4670 and 4830...Also, are there any idications whether all 4830 will be made from partially disabled/defective dies? Or will AMD be fabbing smaller 4830 specific RV770's?
Goty - Saturday, October 25, 2008 - link
I highly doubt AMD would try to produce an entirely new chip for the 4830. The more SKUs you have, the more waste you get. The 4830 is a cost recuperating measure for the dice that don't make the bin for the 4850 or 4870.DerekWilson - Saturday, October 25, 2008 - link
if the 4830 overtakes the 4850 and 4870 combined in volume and amd runs out of parts binned for the lower performance part, they may need to make 4830s out of some GPUs that could handle higher performance.but there's a lot of ifs and such in that one. it's not impossible that some GPUs could be capable of running with all SIMDs enabled. but it might also be impossible to make the card tell the GPU to turn them all on (depending on how AMD has built the thing).
PrinceGaz - Saturday, October 25, 2008 - link
Hehehe, "dice". The last time I used them was in a tabletop D&D session. The last time I used real physical ones you could hold, anyway.The plural of "die" is "dies" for a manufactured physical component like a processor, or anything else for that matter. Pretty much any reliable online (and especially paper) dictionary will agree.
Talking about CPU dice is good for a light-hearted comment, but not for anything else.
Griswold - Sunday, October 26, 2008 - link
No, smartpants. Both works just fine. Open your eyes to the real world and you'll see.Goty - Saturday, October 25, 2008 - link
Most industry documents would disagree.