DeltaChrome S8: First look

WE PREVIEWED S3’s new DeltaChrome graphics chip exactly three months ago. At the time, the DeltaChrome looked like it could become a competent alternative to ATI and NVIDIA’s two-fisted stranglehold on the DirectX 9 graphics market. Instead of looking to challenge for the high-end graphics crown, S3 was preparing a line of mid-range and low-end DeltaChrome products that would balance 3D performance and DirectX 9 compatibility with a suite of new video features and high-definition video output.

On paper, DeltaChrome looked pretty good, but we all know that paper specs and features don’t always fly in the real world.

Although cards based on DeltaChrome won’t be available in the real world until next year, S3 has given us a chance to preview of the chip’s 3D graphics capabilities using an early DeltaChrome S8 sample board with the latest beta drivers from S3. How does the S8’s 3D performance look at this early stage? Read on to find out.

The DeltaChrome S8: A quick refresher course
If you haven’t already, take a moment to read through our initial DeltaChrome preview. Since we’ll only be previewing the chip’s 3D capabilities today, I’ll only cover features related to the 3D pipeline. The DeltaChrome has plenty of other goodies that branch from and extend beyond its graphics pipeline, and we’ll cover those with a full review once retail boards become available.

GPU S3 DeltaChrome S8
Core clock 300MHz
Pixel pipelines 8
Peak pixel fill rate 2400 Mpixels/s
Texture units/pixel pipeline 1
Textures per clock 8
Peak texel fill rate 2400 Mtexels/s
Memory clock 300MHz
Memory type BGA DDR SDRAM
Memory bus width 128-bit
Peak memory bandwidth 9.6GB/s
Ports VGA, DVI, composite and S-Video outputs
Auxiliary power connector None

With eight full pixel pipelines running at 300MHz, the S8 boasts plenty of fill rate. The chip’s 128-bit memory interface is reasonably competitive with the Radeon 9600 Pro and GeForce FX 5700 Ultra. However, unlike the sophisticated crossbar memory controllers employed by ATI and NVIDIA, the DeltaChrome’s memory controller can only access data in 128-bit blocks.

The chips in the DeltaChrome line are all DirectX 9 compatible and include full support for pixel and vertex shader versions 2.0. Pixel shader precision maxes out at 96 bits per pixel, or 24 bits of precision for each of the red, green, and blue color channels, just like ATI’s R3x0 graphics chips. DeltaChrome’s pixel shaders support 128 color instructions per pass, with up to 32 texture instructions and 16 texture lookups, but they can’t branch and loop like NVIDIA’s flexible GeForce FX pixel shaders. DeltaChrome’s pixel shaders do, however, support per-pixel gamma correction.

Since drawing unseen pixels is a waste of valuable resources, the DeltaChrome employs several methods to reduce overdraw. In addition to occlusion culling algorithms that discard hidden pixels early in the rendering pipeline, the DeltaChrome minimizes Z-buffer reads and writes and has a zero-cycle Z-clear. The chip also has some additional overdraw reduction technologies under the hood, but S3 is keeping the details to itself.

Though we won’t be exploring the S8’s antialiasing or anisotropic performance today, the DeltaChrome supports both in hardware. Anisotropic filtering is supported up to 16X, and 4X multi-sampled antialiasing is available at resolutions up to 1024×768. It doesn’t appear that either aniso or AA is available in the current drivers, though.

Amazingly, S3 has managed to squeeze all those features onto a chip with somewhere between 60 and 80 million transistors (for comparison, ATI’s eight-pipe R300 graphics chip weighs in at roughly 110 million transistors). S3 has chosen TSMC to produce the DeltaChrome S8 chip using its 0.13-micron fabrication process.

S3’s DeltaChrome S8 evaluation sample

Anatomy of a sneak peek
Our early DeltaChrome S8 sample came with beta drivers—not exactly a recipe for smooth sailing, as one might expect, since we’re dealing with a brand-new graphics core from company that’s been out of the game for a few years. We came across a number of apparently driver-related issues with image quality, performance, and compatibility. For instance, the S8 wouldn’t cooperate with our nForce3-based graphics testing platform. We also found problems with Call of Duty and with our real-time high dynamic range lighting demo, so we weren’t able to benchmark the card with those apps. (Of course, such problems are a frustratingly intractable part of the graphics game. ATI just released drivers with a fix for Call of Duty, and NVIDIA’s cards have never supported that real-time lighting demo properly.) S3 is already working on fixes for these issues.

Also, S3 readily admits that the card’s OpenGL drivers aren’t quite up to speed yet, but OpenGL performance is expected to improve dramatically with the next major driver release.

S3 has time to perfect its DeltaChrome drivers before cards are available to the public next year, so we remain hopeful. However, some of the problems we encountered do need to resolved before the DeltaChrome is ready for commercial sale. S3 has been working closely with us since we started testing the S8, and judging by the response, we’re fairly confident they’ll have the issues sorted out by the time consumers can actually get their hands on cards.

Not exactly a production board, folks

 

Our testing methods
As ever, we did our best to deliver clean benchmark numbers. Tests were run three times, and the results were averaged.

Our test system was configured like so:

  System
Processor AMD Athlon 64 FX-51 2.2GHz
Front-side bus HT 16-bit/800MHz downstream
HT 16-bit/800MHz upstream
Motherboard MSI K8T Master2-FAR
Chipset VIA K8T800
Chipset drivers VIA 5.1.0.3442
Memory size 1GB (2 DIMMs)
Memory type Corsair XMS3500 PC3200 DDR SDRAM (400MHz)
Graphics card DeltaChrome S8 128MB Radeon 9600 Pro 128MB
Graphics driver S3 15.07.04a CATALYST 3.9
Storage Seagate Barracuda 7200.7 7200RPM SATA hard drive
OS Microsoft Windows XP Professional
OS updates Service Pack 1, DirectX 9.0b

To frame the card against a familiar competitor, I’ve tested it against ATI’s Radeon 9600 Pro. However, until cards and pricing become available next year, it’s hard to know what the S8 will line up against.

It’s important to mention that, at press time, the beta S3 15.07.04a drivers we used for testing weren’t approved by FutureMark for use with 3DMark03. FutureMark has yet to evaluate the drivers in question. Keep in mind that future 3DMark03 patches may combat optimizations in unapproved drivers, which could impact performance in the benchmark.

The test system’s Windows desktop was set at 1024×768 in 32-bit color at a 75Hz screen refresh rate. Vertical refresh sync (vsync) was disabled for all tests.

We used the following versions of our test applications:

All the tests and methods we employed are publicly available and reproducible. If you have questions about our methods, hit our forums to talk with us about them.

 

Fill rate
Theoretical fill rate and memory bandwidth peaks don’t necessarily dictate real-world performance, but they’re a good place to start.

  Core clock (MHz) Pixel pipelines  Peak fill rate (Mpixels/s) Texture units per pixel pipeline Peak fill rate (Mtexels/s) Memory clock (MHz) Memory bus width (bits) Peak memory bandwidth (GB/s)
Radeon 9600 325 4 1300 1 1300 400 128 6.4
GeForce FX 5600 325 4 1300 1 1300 500 128 8.0
Radeon 9000 Pro 275 4 1100 1 1100 550 128 8.8
DeltaChrome S8 300 8 2400 1 2400 600 128 9.6
Radeon 9600 Pro 400 4 1600 1 1600 600 128 9.6
Radeon 9600 XT 500 4 2000 1 2000 600 128 9.6
GeForce FX 5200 Ultra 325 4 1300 1 1300 650 128 10.4
GeForce FX 5600 Ultra 400 4 1600 1 1600 800 128 12.8
GeForce FX 5700 Ultra 475 4 1900 1 1900 906 128 14.4
GeForce FX 5900 XT 400 4 1600 2 3200 700 256 22.4

With eight full pixel pipelines, the DeltaChrome S8 boasts even more theoretical pixel and texel fill rate than ATI’s Radeon 9600 XT. However, the S8’s 128-bit memory path only yields 9.6GB/sec of bandwidth, which is more comparable to a GeForce FX 5600 or Radeon 9000 Pro.

The S8 definitely delivers on its multi-texturing fill rate promise, but its single-texturing fill rate is considerably lower. In fact, this performance looks eerily similar to what one might expect from a 4 x 2-pipe GPU.

Shader performance
3DMark’s synthetic tests will give us our first look at DeltaChrome’s pixel and vertex shader performance in DirectX 9.

The S8 can only manage half the Radeon 9600 Pro’s performance in 3DMark03’s pixel shader 2.0 test. The S8 is more competitive in 3DMark03’s vertex shader test, but it still trails the 9600 Pro slightly. Now, let’s look at how the DeltaChrome S8 performs in real games.

 

Games

Unreal Tournament 2003

The S8 turns in a strong performance in Unreal Tournament 2003, which uses Direct3D rather than OpenGL.

Comanche 4

The S8 turns in a respectable performance in Comanche 4, too.

Quake III Arena

Although it’s playable at lower resolutions, the DeltaChrome can’t turn in big numbers in Quake III Arena. This highlights the fact that the DeltaChrome’s OpenGL drivers still need work, as S3 has acknowledged.

 

Serious Sam SE

We tested Serious Sam SE in OpenGL mode, and the results aren’t surprising given what we saw with Quake III Arena. It’s worth noting that the S8’s frame rates are relatively consistent and flow pretty well across the length of our benchmark demo. We aren’t seeing jerky or choppy performance, just relatively low frame rates.

 

Splinter Cell

The DeltaChrome is running a little behind the curve in Splinter Cell. Honestly, I expected better performance given the fact that Splinter Cell uses Direct3D.

 

3DMark03

The S8 trails ATI’s Radeon 9600 Pro throughout 3DMark03’s game tests.

 

AquaMark3

The S8 isn’t all that far behind the 9600 Pro in AquaMark3.

Halo
I used the “-use20” switch with the Halo benchmark to force the game to use version 2.0 pixel shaders.

DeltaChrome finds itself behind the 9600 Pro in Halo, as well.

Tomb Raider: Angel of Darkness
We’ve used these extreme quality settings from Beyond3D to give the DeltaChrome a thorough workout in this DirectX 9 game.

The S8 wouldn’t run Tomb Raider at 1600×1200, but the card probably wouldn’t have playable frame rates at that resolution, anyway. Given its performance in Halo and AquaMark, I actually expected the S8 to be more competitive in Tomb Raider. However, the card’s performance may be hindered by its problems with rendering the water effects in this demo:

DeltaChrome’s beta drivers need work on this water effect To S3’s credit, the S8 doesn’t have any image quality problems with the rest of our Tomb Raider demo, but the water is hard to miss.

 

ShaderMark 2.0
ShaderMark is a sort of torture test for DirectX 9 pixel shader capabilities. Interestingly enough, the same ShaderMark shaders that won’t run on NVIDIA’s GeForce FX cards also don’t run on the DeltaChrome S8.

The S8’s performance is well behind the Radeon 9600 Pro here.

 

ShaderMark image quality
With its beta drivers, the S8 had problems rendering a number of ShaderMark’s shaders correctly. Of the 14 shader tests it’s able to complete, eight have image quality issues that are easy to spot when compared with the Radeon 9600 Pro’s output.

Below are screenshots of the eight problematic shaders as they’re rendered by the DeltaChrome S8. Move your mouse over the images to see the Radeon 9600 Pro’s output (depending on your connection speed, the Radeon 9600 Pro image may take a second or two to load.) Though the images are compressed JPEGs, they’re sufficient to highlight differences in rendered output.

Per pixel diffuse lighting (move mouse over the image to see the Radeon 9600 Pro’s output)

Point phong lighting (move mouse over the image to see the Radeon 9600 Pro’s output)

Spot phong lighting (move mouse over the image to see the Radeon 9600 Pro’s output)

Directional anisotropic lighting (move mouse over the image to see the Radeon 9600 Pro’s output)

Bump mapping with phong lighting (move mouse over the image to see the Radeon 9600 Pro’s output)

Self shadowing bump mapping with phong lighting (move mouse over the image to see the Radeon 9600 Pro’s output)

Procedural stone shader (move mouse over the image to see the Radeon 9600 Pro’s output)

Procedural wood shader (move mouse over the image to see the Radeon 9600 Pro’s output)

The DeltaChrome’s ShaderMark problems look to be primarily lighting-related, and S3 is working on a driver fix.

 

Image quality done right
Since I’ve pointed out a number of instances where the DeltaChrome’s image quality isn’t up to par, it’s only fair that I highlight where it’s impeccable. Below are screenshots from ShaderMark, 3DMark03, and AquaMark3 illustrating that, when everything works right, the S8 is just as capable of producing gorgeous visuals as ATI’s Radeon 9600 Pro.

ShaderMark 2.0 environment mapping – DeltaChrome S8

ShaderMark 2.0 environment mapping – Radeon 9600 Pro

ShaderMark 2.0 tile shader – DeltaChrome S8

ShaderMark 2.0 tile shader – Radeon 9600 Pro

3DMark03’s Mother Nature frame 1799 – DeltaChrome S8

3DMark03’s Mother Nature frame 1799 – Radeon 9600 Pro

AquaMark3 frame 3600 – DeltaChrome S8

AquaMark3 frame 3600 – Radeon 9600 Pro

 

Conclusions
Well, there you have it. The DeltaChrome is very real, and while S3 is still working to iron out a number of driver issues, the S8’s performance and image quality in some of the applications we tested show the card has potential. Because we’ve only seen the performance of an early sample card with beta drivers, we don’t want to draw too many conclusions. However, we can engage in a little conjecture based on these early results.

The card’s relatively pedestrian memory controller and limited memory bandwidth probably won’t make for a benchmark burner, even when final drivers are released. Still, the DeltaChrome S8’s performance in AquaMark3, Halo, and Unreal Tournament 2003 is promising. Also, despite obvious issues in parts of ShaderMark, the S8 looks to be a legitimate contender in the DirectX 9-class graphics sweeps. We just hope S3’s driver and compiler development teams can boost pixel shader performance a bit. NVIDIA has managed to improve pixel shader performance in its NV3x chips significantly over time, but we’re unsure whether the DeltaChrome would benefit from similar software tuning.

In short, we won’t know whether S3 has a real contender on its hands until we get ours on a retail DeltaChrome S8 board with a final copy of S3’s drivers. We’ll also want to know more about how S3 and its partners will be pricing the various DeltaChrome flavors. S3 still has some work to do to get the DeltaChrome S8 ready for prime time, but we’ll certainly be tuning in when they do. 

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