AMD's Radeon HD 5870: Bringing About the Next Generation Of GPUs
by Ryan Smith on September 23, 2009 9:00 AM EST- Posted in
- GPUs
The Return of Supersample AA
Over the years, the methods used to implement anti-aliasing on video cards have bounced back and forth. The earliest generation of cards such as the 3Dfx Voodoo 4/5 and ATI and NVIDIA’s DirectX 7 parts implemented supersampling, which involved rendering a scene at a higher resolution and scaling it down for display. Using supersampling did a great job of removing aliasing while also slightly improving the overall quality of the image due to the fact that it was sampled at a higher resolution.
But supersampling was expensive, particularly on those early cards. So the next generation implemented multisampling, which instead of rendering a scene at a higher resolution, rendered it at the desired resolution and then sampled polygon edges to find and remove aliasing. The overall quality wasn’t quite as good as supersampling, but it was much faster, with that gap increasing as MSAA implementations became more refined.
Lately we have seen a slow bounce back to the other direction, as MSAA’s imperfections became more noticeable and in need of correction. Here supersampling saw a limited reintroduction, with AMD and NVIDIA using it on certain parts of a frame as part of their Adaptive Anti-Aliasing(AAA) and Supersample Transparency Anti-Aliasing(SSTr) schemes respectively. Here SSAA would be used to smooth out semi-transparent textures, where the textures themselves were the aliasing artifact and MSAA could not work on them since they were not a polygon. This still didn’t completely resolve MSAA’s shortcomings compared to SSAA, but it solved the transparent texture problem. With these technologies the difference between MSAA and SSAA were reduced to MSAA being unable to anti-alias shader output, and MSAA not having the advantages of sampling textures at a higher resolution.
With the 5800 series, things have finally come full circle for AMD. Based upon their SSAA implementation for Adaptive Anti-Aliasing, they have re-implemented SSAA as a full screen anti-aliasing mode. Now gamers can once again access the higher quality anti-aliasing offered by a pure SSAA mode, instead of being limited to the best of what MSAA + AAA could do.
Ultimately the inclusion of this feature on the 5870 comes down to two matters: the card has lots and lots of processing power to throw around, and shader aliasing was the last obstacle that MSAA + AAA could not solve. With the reintroduction of SSAA, AMD is not dropping or downplaying their existing MSAA modes; rather it’s offered as another option, particularly one geared towards use on older games.
“Older games” is an important keyword here, as there is a catch to AMD’s SSAA implementation: It only works under OpenGL and DirectX9. As we found out in our testing and after much head-scratching, it does not work on DX10 or DX11 games. Attempting to utilize it there will result in the game switching to MSAA.
When we asked AMD about this, they cited the fact that DX10 and later give developers much greater control over anti-aliasing patterns, and that using SSAA with these controls may create incompatibility problems. Furthermore the games that can best run with SSAA enabled from a performance standpoint are older titles, making the use of SSAA a more reasonable choice with older games as opposed to newer games. We’re told that AMD will “continue to investigate” implementing a proper version of SSAA for DX10+, but it’s not something we’re expecting any time soon.
Unfortunately, in our testing of AMD’s SSAA mode, there are clearly a few kinks to work out. Our first AA image quality test was going to be the railroad bridge at the beginning of Half Life 2: Episode 2. That scene is full of aliased metal bars, cars, and trees. However as we’re going to lay out in this screenshot, while AMD’s SSAA mode eliminated the aliasing, it also gave the entire image a smooth makeover – too smooth. SSAA isn’t supposed to blur things, it’s only supposed to make things smoother by removing all aliasing in geometry, shaders, and textures alike.
As it turns out this is a freshly discovered bug in their SSAA implementation that affects newer Source-engine games. Presumably we’d see something similar in the rest of The Orange Box, and possibly other HL2 games. This is an unfortunate engine to have a bug in, since Source-engine games tend to be heavily CPU limited anyhow, making them perfect candidates for SSAA. AMD is hoping to have a fix out for this bug soon.
“But wait!” you say. “Doesn’t NVIDIA have SSAA modes too? How would those do?” And indeed you would be right. While NVIDIA dropped official support for SSAA a number of years ago, it has remained as an unofficial feature that can be enabled in Direct3D games, using tools such as nHancer to set the AA mode.
Unfortunately NVIDIA’s SSAA mode isn’t even in the running here, and we’ll show you why.
5870 SSAA
GTX 280 MSAA
GTX 280 SSAA
At the top we have the view from DX9 FSAA Viewer of ATI’s 4x SSAA mode. Notice that it’s a rotated grid with 4 geometry samples (red) and 4 texture samples. Below that we have NVIDIA’s 4x MSAA mode, a rotated grid with 4 geometry samples and a single texture sample. Finally we have NVIDIA’s 4x SSAA mode, an ordered grid with 4 geometry samples and 4 texture samples. For reasons that we won’t get delve into, rotated grids are a better grid layout from a quality standpoint than ordered grids. This is why early implementations of AA using ordered grids were dropped for rotated grids, and is why no one uses ordered grids these days for MSAA.
Furthermore, when actually using NVIDIA's SSAA mode, we ran into some definite quality issues with HL2: Ep2. We're not sure if these are related to the use of an ordered grid or not, but it's a possibility we can't ignore.
If you compare the two shots, with MSAA 4x the scene is almost perfectly anti-aliased, except for some trouble along the bottom/side edge of the railcar. If we switch to SSAA 4x that aliasing is solved, but we have a new problem: all of a sudden a number of fine tree branches have gone missing. While MSAA properly anti-aliased them, SSAA anti-aliased them right out of existence.
For this reason we will not be taking a look at NVIDIA’s SSAA modes. Besides the fact that they’re unofficial in the first place, the use of a rotated grid and the problems in HL2 cement the fact that they’re not suitable for general use.
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SiliconDoc - Thursday, September 24, 2009 - link
Are you seriously going to claim that all ATI are not generally hotter than the nvidia cards ? I don't think you really want to do that, no matter how much you wail about fan speeds.The numbers have been here for a long time and they are all over the net.
When you have a smaller die cranking out the same framerate/video, there is simply no getting around it.
You talked about the 295, as it really is the only nvidia that compares to the ati card in this review in terms of load temp, PERIOD.
In any other sense, the GT8800 would be laughed off the pages comparing it to the 5870.
Furthermore, one merely needs to look at the WATTAGE of the cards, and that is more than a plenty accurate measuring stick for heat on load, divided by surface area of the core.
No, I'm not the one not thinking, I'm not the one TROLLING, the TROLLING is in the ARTICLE, and the YEAR plus of covering up LIES we've had concerning this very issue.
Nvidia cards run cooler, ati cards run hotter, PERIOD.
You people want it in every direction, with every lying whine for your red god, so pick one or the other:
1.The core sizes are equivalent, or 2. the giant expensive dies of nvidia run cooler compared to the "efficient" "new technology" "packing the data in" smaller, tiny, cheap, profit margin producing ATI cores.
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NOW, it doesn't matter what lies or spin you place upon the facts, the truth is absolutely apparent, and you WON'T be changing the physical laws of the universe with your whining spin for ati, and neither will the trolling in the article. I'm going to stick my head in the sand and SCREAM LOUDLY because I CAN'T HANDLE anyone with a lick of intelligence NOT AGREEING WITH ME! I LOVE TO LIE AND TYPE IN CAPS BECAUSE THAT'S HOW WE ROLL IN ILLINOIS!
SiliconDoc - Friday, September 25, 2009 - link
Well that is amazing, now a mod or site master has edited my text.Wow.
erple2 - Friday, September 25, 2009 - link
This just gets better and better...Ultimately, the true measure of how much waste heat a card generates will have to look at the power draw of the card, tempered with the output work that it's doing (aka FPS in whatever benchmark you're looking at). Since I haven't seen that kind of comparison, it's impossible to say anything at all about the relative heat output of any card. So your conclusions are simply biased towards what you think is important (and that should be abundantly clear).
Given that one must look at the performance per watt. Since the only wattage figures we have are for OCCT or WoW playing, so that's all the conclusions one can make from this article. Since I didn't see the results from the OCCT test (in a nice, convenient FPS measure), we get the following:
5870: 73 fps at 295 watts = 247 FPS per milliwatt
275: 44.3 fps at 317 watts = 140 FPS per milliwatt
285: 45.7 fps at 323 watts = 137 FPS per milliwatt
295: 68.9 fps at 380 watts = 181 FPS per milliwatt
That means that the 5870 wins by at least 36% over the other 3 cards. That means that for this observation, the 5870 is, in fact, the most efficient of these cards. It therefore generates less heat than the other 3 cards. Looking at the temperatures of the cards, that strictly measures the efficiency of the cooler, not the efficiency of the actual card itself.
You can say that you think that I'm biased, but ultimately, that's the data I have to go on, and therefore that's the conclusions that can be made. Unfortunately, there's nothing in your post (or more or less all of your posts) that can be verified by any of the information gleaned from the article, and therefore, your conclusions are simply biased speculation.
SiliconDoc - Saturday, September 26, 2009 - link
4780, 55nm, 256mm die, 150watts HOTG260, 55nm, 576mm die, 171watts COLD
3870, 55nm, 192mm die, 106watts HOT
That's all the further I should have to go.
3870 has THE LOWEST LOAD POWER USEAGE ON THE CHARTS
- but it is still 90C, at the very peak of heat,
because it has THE TINIEST CORE !
THE SMALLEST CORE IN THE WHOLE DANG BEJEEBER ARTICLE !
It also has the lowest framerate - so there goes that erple theory.
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The anomlies you will notice if you look, are due to nm size, memory amount on board (less electricity used by the memory means the core used more), and one slot vs two slot coolers, as examples, but the basic laws of physics cannot be thrown out the window because you feel like doing it, nor can idiotic ideas like framerate come close to predicting core temp and it's heat density at load.
Older cpu's may have horrible framerates and horribly high temps, for instance. The 4850 frames do not equal the 4870's, but their core temp/heat density envelope is very close to indentical ( SAME CORE SIZE > the 4850 having some die shaders disabled and ddr3, the 4870 with ddr5 full core active more watts for mem and shaders, but the same PHYSICAL ISSUES - small core, high wattage for area, high heat)
erple2 - Tuesday, September 29, 2009 - link
I didn't say that the 3870 was the most efficient card. I was talking about the 5870. If you actually read what I had typed, I did mention that you have to look at how much work the card is doing while consuming that amount of power, not just temperatures and wattage.You sir, are a Nazi.
Actually, once you start talking about heat density at load, you MUST look at the efficiency of the card at converting electricity into whatever it's supposed to be doing (other than heating your office). Sadly, the only real way that we have to abstractly measure the work the card is doing is "FPS". I'm not saying that FPS predict core temperature.
SiliconDoc - Wednesday, September 30, 2009 - link
No, the efficiency of conversion you talk about has NOTHING to do with core temp AT ALL. The card could be massively efficient or inefficient at produced framerate, or just ERROR OUT with a sick loop in the core, and THAT HAS ABSOLUTELY NOTHING TO DO WITH THE CORE TEMP. IT RESTS ON WATTS CONSUMED EVEN IF FRAMERATE OUTPUT IS ZERO OR 300SECOND.(your mind seems to have imagined that if the red god is slinging massive frames "out the dvi port" a giant surge of electricity flows through it to the monitor, and therefore "does not heat the card")
I suggest you examine that lunatic red notion.
What YOU must look at is a red rooster rooter rimshot, in order that your self deception and massive mistake and face saving is in place, for you. At least JaredWalton had the sense to quietly skitter away.
Well, being wrong forever and never realizing a thing is perhaps the worst road to take.
PS - Being correct and making sure the truth is defended has nothing to do with some REDEYE cleche, and I certainly doubt the Gregalouge would embrace red rooster canada card bottom line crumbled for years ever more in a row, and diss big green corporate profits, as we both obviously know.
" at converting electricity into whatever it's supposed to be doing (other than heating your office). "
ONCE IT CONVERTS ELECTRICITY, AS IN "SHOWS IT USED MORE WATTS" it doesn't matter one ding dang smidgen what framerate is,
it could loop sand in the core and give you NO screeen output,
and it would still heat up while it "sat on it's lazy", tarding upon itself.
The card does not POWER the monitor and have the monitor carry more and more of the heat burden if the GPU sends out some sizzly framerates and the "non-used up watts" don't go sailing out the cards connector to the monitor so that "heat generation winds up somewhere else".
When the programmers optimize a DRIVER, and the same GPU core suddenly sends out 5 more fps everything else being the same, it may or may not increase or decrease POWER USEAGE. It can go ANY WAY. Up, down, or stay the same.
If they code in more proper "buffer fills" so the core is hammered solid, instead of flakey filling, the framerate goes up - and so does the temp!
If they optimize for instance, an algorythm that better predicts what does not need to be drawn as it rests behind another image on top of it, framerate goes up, while temp and wattage used GOES DOWN.
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Even with all of that, THERE IS ONLY ONE PLACE FOR THE HEAT TO ARISE... AND IT AIN'T OUT THE DANG CABLE TO THE MONITOR!
SiliconDoc - Friday, September 25, 2009 - link
You can modify that, or be more accurate, by using core mass, (including thickness of the competing dies) - since the core mass is what consumes the electricity, and generates heat. A smaller mass (or die size, almost exclusively referred to in terms of surface area with the assumption that thickness is identical or near so) winds up getting hotter in terms of degrees of Celcius when consuming a similar amount of electricity.Doesn't matter if one frame, none, or a thousand reach your eyes on the monitor.
That's reality, not hokum. That's why ATI cores run hotter, they are smaller and consume a similar amount of electricty, that winds up as heat in a smaller mass, that means hotter.
Also, in actuality, the ATI heatsinks in a general sense, have to be able to dissipate more heat with less surface area as a transfer medium, to maintain the same core temps as the larger nvidia cores and HS areas, so indeed, should actually be "better stock" fans and HS.
I suspect they are slightly better as a general rule, but fail to excel enough to bring core load temps to nvidia general levels.
erple2 - Friday, September 25, 2009 - link
You understand that if there were no heatsink/cooling device on a GPU, it would heat up to crazy levels, far more than would be "healthy" for any silicon part, right? And you understand that measuring the efficiency of a part involves a pretty strong correlation between the input power draw of the card vs. the work that the card produces (which we can really only measure based on the output of the card, namely FPS), right?So I'm not sure that your argument means anything at all?
Curiously, the output wattage listed is for the entire system, not just for the card. Which means that the actual differences between the ATI cards vs. the nvidia cards is even larger (as a percentage, at least). I don't know what the "baseline" power consumption of the system (sans video card) is for the system acting as the test bed is.
Ultimately, the amount of electricity running through the GPU doesn't necessarily tell you how much heat the processors generate. It's dependent on how much of that power is "wasted" as heat energy (that's Thermodynamics for you). The only way to really measure the heat production of the GPU is to determine how much power is "wasted" as heat. Curiously, you can't measure that by measuring the temperature of the GPU. Well, you CAN, but you'd have to remove the Heatsink (and Fan). Which, for ANY GPU made in the last 15 years, would cook it. Since that's not a viable alternative, you simply can't make broad conclusions about which chip is "hotter" than another. And that is why your conclusions are inconclusive.
BTW, the 5870 consumes "less" power than the 275, 285 and 295 GPUs (at least, when playing WoW).
I understand that there may be higher wattage per square millimeter flowing through the 5870 than the GTX cards, but I don't see how that measurement alone is enough to state whether the 5870 actually gets hotter.
SiliconDoc - Saturday, September 26, 2009 - link
Take a look at SIZE my friend.http://www.hardforum.com/showthread.php?t=1325165">http://www.hardforum.com/showthread.php?t=1325165
There's just no getting around the fact that the more joules of heat in any time period (wattage used!= amount of joules over time!) that go into a smaller area, the hotter it gets, faster !
Nothing changes this, no red rooster imagination will ever change it.
SiliconDoc - Saturday, September 26, 2009 - link
NO, WRONG." Ultimately, the true measure of how much waste heat a card generates will have to look at the power draw of the card, tempered with the output work that it's doing (aka FPS in whatever benchmark you're looking at)."
NO, WRONG.
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Look at any of the cards power draw in idle or load. They heat up no matter how much "work" you claim they do, by looking at any framerate, because they don't draw the power unless they USE THE POWER. That's the law that includes what useage of electricity MEANS for the law of thermodynamics, or for E=MC2.
DUHHHHH.
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If you're so bent on making idiotic calculations and applying them to the wrong ideas and conclusions, why don't you take core die size and divide by watts (the watts the companies issue or take it from the load charts), like you should ?
I know why. We all know why.
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The same thing is beyond absolutely apparent in CPU's, their TDP, their die size, and their heat envelope, including their nm design size.
DUHHH. It's like talking to a red fanboy who cannot face reality, once again.