ATI Radeon HD 2900 XT: Calling a Spade a Spade
by Derek Wilson on May 14, 2007 12:04 PM EST- Posted in
- GPUs
General Image Quality
Beyond antialiasing, there are quite a number of factors that go into making real-time 3D look good. Real-time graphics are an optimization problem, and the balance between performance and quality is very important. There is no single "right" way to do graphics, and AMD and NVIDIA must listen carefully to developers and consumers to deliver what they believe is the sweet spot between doing things fast and doing things accurately.
NVIDIA currently offers much more customizable image quality. Users are able to turn on and off different optimizations as they see fit. AMD really only offers a couple specific settings that affect image quality, while most of their optimizations are handled on a per game basis by the ominous feature known as Catalyst A.I. The options we have are disabled, standard and advanced. This doesn't really tell us what is going on behind the scenes, but we leave this setting on standard for all of our tests, as this is the default setting and most users will leave it alone.
Aside from optimizations, texture filtering plays a large role in image quality when high levels of filtering are called for. It's trivial to point sample or bilinear filter, and no one skimps on these duties, but when we get to trilinear and anisotropic filtering the number of texture samples we need and the number of calculations we must perform per pixel go up very quickly. In order to mitigate the cost of these operations, both AMD and NVIDIA attempt to apply high levels of filtering where they are needed and not-so-high levels of filtering where it won't matter that much. Of course there is much debate over where to draw the lines here, and NVIDIA and AMD both choose different paths.
To investigate texture filtering quality, we have employed the trusty D3D AF-Tester. This long-lived application enables us to look at one texture with different colored mipmap levels to see how hardware handles filtering them under different settings. Thankfully, we don't have to talk about angle dependent anisotropic filtering (which is actually a contradiction in terms anyway). AMD and NVIDIA both finally do good quality anisotropic filtering that results in higher resolutions textures being used more of the time where possible. Take a look at these images to see how the different hardware stacks up.
NVIDIA G80 Tunnel 8x/16x AF
G80
R5xx
R6xx
It still looks like NVIDIA is doing slightly more angle independence filtering. In practice, it will be very difficult to tell the difference between an image rendered on AMD hardware and one rendered on NVIDIA hardware. We can also see that AMD has slightly tweaked their AF technique to eliminate some of the odd transitions we noticed on R5xx hardware. This comes through a little better if we look at a flat plane:
AMD R600 Plane 8x AF
R5xx
R6xx
We did happen to notice at least one image quality issue not related to texture filtering on AMD hardware. The problem turns up in Rainbow Six: Vegas in the form of very bad banding where we should see HDR lighting. We didn't notice this problem on G80, as we can see from our comparison.
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We also noticed a small issue with Oblivion at one point where the oblivion gate shader would bleed through other objects, but this was not reproducible and we couldn't get a screenshot of it. This means it could be a game related issue rather than a hardware or driver problem. We'll keep our eyes peeled.
Overall IQ of the current DX10 hardware available is quite good, but we will continue to dig further into the matter to make sure that everything stays that way. We're also waiting for DX10 games before we can determine if there are other differences, but hopefully that won't be the case as DX10 has a single set of requirements.
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mostlyprudent - Monday, May 14, 2007 - link
Frankly, neither the NVIDIA nor the AMD part at this price point is all that impressive an upgrade from the prior generations. We keep hearing that we will have to wait for DX10 titles to know the real performance of these cards, but I suspect that by the time DX10 titles are on the shelves we will have at least product line refreshes by both companies. Does anyone else feel like the graphics card industry is jerking our chains?johnsonx - Monday, May 14, 2007 - link
It seems pretty obvious that AMD needs a Radeon HD2900Pro to fill in the gap between the 2900XT and 2600XT. Use R600 silicon, give it 256Mb RAM with a 256-bit memory bus. Lower the clocks 15% so that power consumption will be lower, and so that chips that don't bin at full XT speeds can be used. Price at $250-$300. It would own the upper-midrange segment over the 8600GTS, and eat into the 8800GTS 320's lunch as well.GlassHouse69 - Monday, May 14, 2007 - link
If I know this, and YOU know this.... wouldnt anandtech? I see money under the table or utter stupidity at work at anand. I mean, I know that the .01+ version does a lot better in benches as well as the higher res with aa/af on sometimes get BETTER framerates than lower res, no aa/af settings. This is a driver thing. If I know this, you know this, anand must. I would rather admit to being corrupt rather than that stupid.GlassHouse69 - Monday, May 14, 2007 - link
wrong section. dt is doing that today it seems to a few peoplexfiver - Monday, May 14, 2007 - link
Hi, thank you for a really in depth review. While reading other 'earlier' reviews I remember a site using Catalyst 8.38 and reported performance improvements upto 14% from 8.37. Look forward to Anandtech's view on this.xfiver - Monday, May 14, 2007 - link
My apologies it was VR zone and 8.36 to 8.37 (not 8.38)GlassHouse69 - Monday, May 14, 2007 - link
If I know this, and YOU know this.... wouldnt anandtech? I see money under the table or utter stupidity at work at anand. I mean, I know that the .01+ version does a lot better in benches as well as the higher res with aa/af on sometimes get BETTER framerates than lower res, no aa/af settings. This is a driver thing. If I know this, you know this, anand must. I would rather admit to being corrupt rather than that stupid.Gary Key - Tuesday, May 15, 2007 - link
I have worked extensively with four 8.37 releases and now the 8.38 release for the upcoming P35 release article. The 8.37.4.2 alpha driver had the top performance in SM3.0 heavy apps but was not very stable with numerous games, especially under Vista. The released 8.37.4.3 driver on AMD's website is the most stable driver to date and has decent performance but nothing near the alpha 8.37 or beta 8.38. The 8.38s offer great benchmark performance in the 3DMarks, several games, and a couple of DX10 benchmarks from AMD.
However, the 8.38s more or less broke CrossFire, OpenGL, and video acceleration in Vista depending upon the app and IQ is not always perfect. While there is a great deal of promise in their performance and we see the potential, they are still Beta drivers that have a long ways to go in certain areas before their final release date of 5/23 (internal target).
That said, would you rather see impressive results in 3DMarks or have someone tell you the truth about the development progress or lack of it with the drivers. As much as I would like to see this card's performance improve immediately, it is what it is at this time with the released drivers. AMD/ATI will improve the performance of the card with better drivers but until they are released our only choice is to go with what they sent. We said the same thing about NVIDIA's early driver issues with the G80 so there are not any fanboys or people taking money under the table around here. You can put all the lipstick on a pig you want, but in the end, you still have a pig. ;-)
Anand Lal Shimpi - Monday, May 14, 2007 - link
There's nothing sinister going on, ATI gave us 8.37 to test with and told us to use it. We got 8.38 today and are currently testing it for a follow-up.Take care,
Anand
GlassHouse69 - Monday, May 14, 2007 - link
wow dood. you replied!Yes, I have been wondering about the ethics of your group here for about a year now. I felt this sorta slick leaning towards and masking thing goign on. Nice to see there is not.
Thanks for the 1000's of articles and tests!
-Mr. Glass