Right, though flops/watt isn't really a very good metric for the main purpose of these chips (which are, after all, mostly still intended for 3d graphic cards).
AMD: R7xx Speculation
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Well flops and watts probably mean nothing to 95% of people who are going to buy these things. So perhaps they are thinking of building a box for pixar or something.
There are some oddities with the power consumption part of the review (GX2 numbers seem off from expected) we've been looking at though so I'd like to see some corroboration before jumping to any conclusions.
I think we should wait for official reviews with release drivers before assuming anything with regards to idle power consumption.
And now that RV770 has been dealt with, what can we really spect from R700? Is nVidia in even more trouble than we though? Interesting indeed.
I would pick a 4870 if i have some free time this summer (which i don't sadly).
And now that RV770 has been dealt with, what can we really spect from R700? Is nVidia in even more trouble than we though? Interesting indeed.
I would pick a 4870 if i have some free time this summer (which i don't sadly).
I'll answer instead
I don't even know where to start describing all the differences - I don't think I'm alone not having expected that many changes.
1) tmu organization. No longer shared across arrays, each array has its own quad tmu. I'll bet the sampler thread arbiter had to change with that as well.
2) tmu themselves changed. While they always had separate L1 caches (I think - the picture is misleading), now the separate 4 TA and point sampling fetch units are gone (thus one tmu is 4 TA, 16 fetch, 4 TF instead of 8 TA, 20 fetch, 4 TF). Also, early tests indicate they are no longer capable of sampling fp16 at full speed (dropping to half and one quarter at fp32 IIRC).
3) ROPs. They now have 4xZ fill capability (at least in some situations) instead of just 2. The R600 picture indicates a fog/alpha unit which is now gone, though I doubt it really was there in the first place (doesn't make sense should be handled in the shader ALU). The picture also indicate shared color cache for R600, I don't know if this was true however. Could be though (see next item).
4) no more ring bus. Clearly with rv770 ROPs are tied to memory channels (just like nvidia G80 and up), and there are per-memory channel L2 texture caches. Instead of one ring-bus it seems there's now different "busses" or crossbars or whatever for different data (it's hot a "hub", it's got some path for texture data etc.)
5) Other stuff like the local data store, read/write cache etc.
That seems like the most important to me, architecture-wise (of course it got 10 shader arrays instead of 4 too...)
thanks., mczak...actually I tried to understand what goes wrong in R600 ( hope this evil never come back in future (ati)/(and why not nvidia) chips)... what you said, it is a start...hope more investigation will come in the next days....
Why so big? I thought GT200 only had about 45% more transistors than the 4800?
And doesn't G92b have 200 million less than rv770? Perhaps its just a difference in counting methods, or perhaps its ATi showing their experience at 55nm.
1 - It's still on 65nm node.
2 - There is more "fillrate" hardware (hard to pack in dense structures), like ROPs and TMUs, than any GPU up to date.
3 - Beefy memory interface -- the primal enemy of any effective die shrink.
Mintmaster
Veteran
There will always be differences between what ATI and NVidia do when determining transistor count. Usually, density of one company's chips at a particular process node stays the same, though, because they're generally pretty consistent.
G92 has similar transistors/mm2 to GT200, and the same is true for RV670/RV770. Looking at G92b for scaling of GT200b makes more sense than looking at RV770.
Silent_Buddha
Legend
They don't seem to be quite so densely packed in comparison to Rv770. If someone had mentioned a couple months ago that Rv770 would be approaching 1 billion transistors and still be 271mm^2 or smaller (I think consensus is that it's much smaller than 271mm^2), most people would have laughed and dismissed it as a pipe dream.
Regards,
SB
VoltMod: HD 4850 OC @ 800 MHz core / 1100 MHz memory -> screenshot
Any idea what cooling was used? It's clearly not Ln2, but I'm wondering if they went to a beefier air cooler or water or something. Temps certainly don't seem bad at that speed.
ChronoReverse
Newcomer
What did they use to overclock past 700MHz?
What was the stock and what the modded voltage?
Default : 2D = 500MHz @ 1.08V, 3D = 625MHz @ 1.19V.
toTOW Vmod -> (UP6201BQ) 100 KOhms, +0.025V.
Heatsink = Zalman VF700CU
HD 4850 + Zalman Heatsink -> Photo1, Photo2.
725 MHz @ 1.200V -> Screenshot
775 MHz @ 1.265V -> Screenshot
800 MHz @ 1.???V -> Screenshot
New Trojan Horse
toTOW Vmod -> (UP6201BQ) 100 KOhms, +0.025V.
Heatsink = Zalman VF700CU
HD 4850 + Zalman Heatsink -> Photo1, Photo2.
725 MHz @ 1.200V -> Screenshot
775 MHz @ 1.265V -> Screenshot
800 MHz @ 1.???V -> Screenshot
New Trojan Horse
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That's interesting. A lot of those changes make the general setup a lot more similiar to G8x. Makes for easier comparisons I guess.
I don't think FP16 filtering is half speed in RV770 though. Measured numbers seem to indicate that it's pushing more texels than G92 and it gets up pretty close to GT200 too.
jimmyjames123
Regular
While I agree that GTX 280 is way overpriced, let's not get carried away and claim that GTX 260 is DOA. I'm sure when all is said and done that there will end up being several games where the GTX 260 has higher playable settings than the 4870 512MB, not to mention possibly lower idle power and also PhysX/CUDA support. That's not to take anything away from the HD 4870, which I'm sure is a great card and great value. But to simply look at max/average framerate like the chinese review really doesn't tell us the full story anyway. Also note that any review that compares Geforce GT200 vs Radeon 48xx with 8x MSAA enabled will almost always show advantages for the Radeon. As mentioned before, it doesn't make sense to run the Geforce cards with 8x MSAA, as performance is much much better with 16x CSAA, with minimal tradeoff in image quality.
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Well flops and watts probably mean nothing to 95% of people who are going to buy these things. So perhaps they are thinking of building a box for pixar or something.
There are some oddities with the power consumption part of the review (GX2 numbers seem off from expected) we've been looking at though so I'd like to see some corroboration before jumping to any conclusions.
I think so.
Look at the consumption test made by this very reliable italian site.
How can in the world the HD4870 consume more than a HD3870X2... This diagram shows clearly that is the idle consuption the problem, not the full. But the idle power draw can be fixed with a simple driver issue.
There's something very fishy in that test...
jimmyjames123
Regular
This cycle will never end. Considering that 9800 GTX+ is said to have very good headroom for overclocking, maybe vendors will come out with 9800 GTX+ OC versions too. That will certainly be a very good value compared to GT200.
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