 | |||
|
|
|
|
|
 |
ATI Super AA vs. NVIDIA SLI Anti-Aliasing January 17, 2006 |
|
 |
|
| |
Summary: Curious to see how ATI's new Super AA modes compare to NVIDIA's SLI Anti-Aliasing? If so, you may want to check out today's article. We've paired NVIDIA's latest GeForce 7800 GTX 256MB and 512MB cards against ATI's CrossFire X1800 XT. We've got 4x, 8x, 14x, and 16xAA screenshots as well as performance. See how the latest cards look and perform in this article!
 Introduction | Page:: ( 1 / 15 ) |
Some cynics may wonder why the need for such insanely high AA modes. After all, when combined with a high screen resolution such as 1600x1200/2048x1536 for 20”+ LCD/CRT users, and 1680x1050 or 1920x1200 for widescreen LCDs, 4xAA looks pretty good already. But “pretty good” isn’t enough for some gamers. In addition, some games need all the help they can get to combat jaggies. Racing/sports titles for instance, as well as flight sims and some shooters where most of the combat takes place in brighter environments where jaggies are more apparent. Examples of this would include Counter-Strike: Source and Battlefield 2.
These are all situations where 4xAA may not be quite enough for some gamers.
But another reason why AA modes like SLI anti-aliasing and Super AA are becoming more feasible is because today’s latest graphics cards are well ahead of all but the most-intensive games. High-end cards like the GeForce 7800 GTX 512MB and Radeon X1800 XT are frequently CPU-limited in single-card configurations in games such as Half-Life 2. Once you combine two cards in your system, the problem becomes even worse, even with the latest CPUs on the market today – as you crank up the screen resolution, the frame rate stays the same because the CPU can’t keep the graphics card fed with data quickly enough (or in some cases due to poor programming by the game developer, but that’s an entirely different story), in some cases at resolutions as high as 1280x1024!
But if you could crank up the AA to say, 8x or 10xAA (or more) the burden shifts more on the graphics card, keeping your system’s components in balance and giving you better visuals in the process. That’s the theory at least. Up until the latest generation of GeForce 7 and Radeon X1800 graphics cards were released last year, GPUs weren’t quite up to the challenge of tackling these AA modes while delivering fluid frame rates, but as we showed you in our X1800 CrossFire story, not only is the X1800 CrossFire setup capable of confronting this test, it actually handles these AA modes with aplomb. Let’s start by taking a look at some screenshots…
| AA Screenshots | Page:: ( 2 / 15 ) |
First things first, while we’re using screenshots today to help illustrate ATI and NVIDIA’s dual-GPU AA rendering modes, we should reiterate that when you’re dealing with AA levels as high as we are in this article the differences between the AA levels are easiest to see when the game is running in motion rather than in a static screenshot. Screenshots just don’t do the AA modes justice, particularly at the higher AA levels.
We should also note that ATI and NVIDIA’s newer AA modes, while similar, don’t symmetrically correspond to each other. On NVIDIA setups for instance, two SLI antialiasing modes are available, an 8x setting and a 16x setting.
ATI’s CrossFire implementation is somewhat similar. When running in CrossFire mode, both Radeon graphics cards use slightly different sampling patterns which are then blended together by the compositing engine found on the CrossFire master card to produce the final image, ultimately providing sharper visuals. CrossFire also supports 8x, 10, 12x, and 14x AA modes. For CrossFire’s 8xAA mode, both cards are running in 4xAA mode, for an effective equivalent of 8xAA likewise at 12xAA, both cards are running in 6x mode. The 10x and 14x modes mix multisampling with supersampling for even better image quality. At the 10x setting for example, the cards mix 8x multisampling with 2x supersampling, while 14x combines 12x multisampling with 2x supersampling.
For X1800 XT CrossFire, the compositing engine has a more powerful FPGA chip that more powerful than its predecessor. The new FPGA has been designed to handle the blending used for CrossFire’s Super AA mode, resulting in little or no performance hit for SuperAA in some cases. Let’s take a look at those screenshots though, first with 4xAA:
[image]
| <% print_image("01"); %> | <% print_image("02"); %> |
Nothing much to say here, we’re starting with Lock On: Modern Air Combat first as it has proven to be a title that’s pretty good at illustrating the subtle variations in AA quality between ATI and NVIDIA hardware. We should also note that graphics quality settings were the same for both cards, with the screenshots taken using the game’s highest quality graphics settings. The heat haze from the engine exhaust didn’t show up properly in some of our ATI screenshots regardless of the method used to record screenshots, but the haze effect was definitely present on screen when the screenshots were taken. You'll also notice the banding on the tail of the F-15C (the swirly lines) this is another image capture bug that wasn't seen during actual gameplay. Under 4xAA, image quality from both cards is pretty close, each card has their areas that they render better than the other. Take a look at this example in favor of the Radeon X1800 XT:
Radeon X1800 XT 4xAA
GeForce 7800 GTX 512MB 4xAA
Look just behind the air intake, right where the intake meets the F-15C’s fuselage. This area of the screenshot clearly favors ATI. But what happens when you focus on a different portion of the same screenshot? Now let’s look at this screenshot taken from a different portion of the F-15C in favor of the GeForce 7800 GTX 512MB:
Radeon X1800 XT 4xAA
GeForce 7800 GTX 512MB 4xAA
In this screenshot, check out the trailing (back) edge of the F-15C’s wing, as well as the shadow underneath. This is a case that favors GeForce 7800 GTX 512MB (although the shadow underneath the F-15C’s wingtip looks better on X1800).
| 8x/14x/16xAA Screenshots | Page:: ( 3 / 15 ) |
[image]
| <% print_image("03"); %> | <% print_image("04"); %> |
Under each card’s respective AA modes, both continue to excel in the areas we looked at previously. In the case of the X1800 XT, the air intakes on the F-15C clearly favors the ATI card, whereas the left wing still looks sharper on GeForce 7800 GTX 512MB. Therefore instead of going head-to-head, ATI versus NVIDIA, let’s look at the progression of going from 4xAA to 8xAA on both cards.
First ATI:
Radeon X1800 XT 512MB 4xAA (left) vs 8xAA (right)
Now NVIDIA:
GeForce 7800 GTX 512MB 4xAA (left) vs 8xAA (right)
Take a look at the F-15C’s shadow just underneath the plane’s wing. Both ATI and NVIDIA’s 8xAA modes clean up the jagged edges on the shadows just a little better under the 8x setting than under 4xAA. When you crank it up to 16x, the visuals get even sharper:
[image]
| <% print_image("05"); %> | <% print_image("06"); %> |
Radeon X1800 XT 512MB 8xAA (left) vs 14xAA (right)
And from another portion of the F-15C:
Radeon X1800 XT 512MB 8xAA (left) vs 14xAA (right)
See how that one access panel line sparkles on the center of the F-15C’s fuselage with ATI’s 8x setting? It lies just behind the air intake, to the right of the F-15C’s aerial refueling door and the blue camouflage. Under 14xAA the sparkling is gone. Let’s take a look at the GeForce 7800 GTX 512MB:
GeForce 7800 GTX 512MB 4xAA (left) vs 8xAA (right)
And from another portion of the F-15C:
GeForce 7800 GTX 512MB 4xAA vs 8xAA
Edges along the F-15C’s air intake look sharper once NVIDIA’s 16xAA is applied. Particularly at the top.
We also took some screenshots with Half-Life 2 and Quake 4, although they don’t illustrate the differences quite as well as LOMAC:
[image]
| <% print_image("07"); %> | <% print_image("08"); %> |
| <% print_image("09"); %> | <% print_image("10"); %> |
| <% print_image("11"); %> | <% print_image("12"); %> |
| <% print_image("13"); %> | <% print_image("14"); %> | <% print_image("15"); %> |
| <% print_image("16"); %> | <% print_image("17"); %> |
| Test Systems | Page:: ( 4 / 15 ) |
System Setup
AMD Athlon 64 FX-55
ASUS A8N32-SLI Deluxe (for NVIDIA cards)
ASUS A8R-MVP (for ATI cards)
2GB OCZ DDR400 SDRAM
ATI Radeon X1800 XL 256MB
ATI Radeon X1800 XT 512MB
ATI Radeon X1800 XT CrossFire Edition 512MB
CATALYST 5.13
NVIDIA GeForce 7800 GTX 512MB
NVIDIA GeForce 7800 GTX
NVIDIA GeForce 7800 GT
Driver version ForceWare 81.98
250GB Maxtor Hard Drive Maxline III SATA Hard Drive w/16MB Cache
Windows XP Professional SP1
DirectX 9.0c
Benchmarks
IL-2 Sturmovik: Forgotten Battles
Half-Life 2
F.E.A.R.
Battlefield 2
Quake 4
| Half-Life 2 4xAA/16xAF vs 8xAA/16xAF | Page:: ( 5 / 15 ) |
Half-Life 2 – Direct3D
| Battlefield 2 4xAA/16xAF vs 8xAA/16xAF | Page:: ( 6 / 15 ) |
Battlefield 2 – Direct3D
| Quake 4 4xAA/16xAF vs 8xAA/16xAF | Page:: ( 7 / 15 ) |
Quake 4 – OpenGL
| IL-2 4xAA/16xAF vs 8xAA/16xAF | Page:: ( 8 / 15 ) |
IL-2: FB – OpenGL
| F.E.A.R. 4xAA/16xAF vs 8xAA/16xAF | Page:: ( 9 / 15 ) |
F.E.A.R. – Direct3D
| HL2 4xAA/16xAF vs 14&16xAA/16xAF | Page:: ( 10 / 15 ) |
Half-Life 2 – Direct3D
| Battlefield 2 4xAA/16xAF vs 14&16xAA/16xAF | Page:: ( 11 / 15 ) |
Battlefield 2 – Direct3D
| Quake 4 4xAA/16xAF vs 14&16xAA/16xAF | Page:: ( 12 / 15 ) |
Quake 4 – OpenGL
| IL-2 4xAA 4xAA/16xAF vs 14&16xAA/16xAF | Page:: ( 13 / 15 ) |
IL-2: FB – OpenGL
| F.E.A.R. 4xAA/16xAF vs 14&16xAA/16xAF | Page:: ( 14 / 15 ) |
F.E.A.R. – Direct3D
| Final thoughts | Page:: ( 15 / 15 ) |
Even 14xAA is quite playable at resolutions as high as 1280x1024 in some games. You can’t really say this for the GeForce 7800 GTX 512MB with 16xAA.
The visuals outputted by both ATI and NVIDIA’s newer AA modes are impressive, particularly when seen while up and running in motion inside games. Jaggies tend to do all sorts of annoying things in motion such as crawling and sparkling. Because of this, our screenshots we’ve provided really only show part of the story when it comes to image quality.
As we noted in our Radeon X1800 CrossFire story though, NVIDIA’s key advantage they have over ATI CrossFire is infrastructure support. Since it’s been around for over a year now, NVIDIA’s SLI ecosystem is not only more mature, it’s considerably more robust as well. You can find SLI motherboards starting right around $100, all the way up to nearly $200, while the boards themselves are often more feature-complete as well. ATI on the other hand only has a handful of CrossFire motherboards on the retail market at the moment, and as such, they tend to sell for higher prices than a comparable nForce4 SLI motherboard.
ATI’s CrossFire implementation isn’t as elegant as NVIDIA SLI either. In the case of X1800 CrossFire, you have to mess with thick dongles to connect both graphics cards to each other, while only ATI’s flagship X1800 XT has a corresponding CrossFire master board to pair it with. This leaves ATI X1800 XL users out in the cold unless they want to pay $100+ more for a X1800 XT CrossFire card that will be running with half its memory disabled. With NVIDIA you can mix and match cards as long as they’re based on the same GPU: you don’t need to pair the GeForce 7800 GT for example to a more expensive master card to get SLI to work.
Until CrossFire’s infrastructure catches up to SLI, we have a feeling that ATI’s CrossFire technology will continue to play second fiddle to NVIDIA SLI despite ATI’s superior performance in higher AA modes. Gamers looking for the best combination of image quality and performance though should definitely consider ATI’s CrossFire solution. Because as it stands now, ATI’s got the edge over NVIDIA when it comes to this.