It has nearly been one full year since we first brought you details of S3’s DeltaChrome. First slated for arrival at the end of the 2nd quarter of this year, slowly but surely the release date has been pushed back further and further. Fortunately for S3, that wait is about to come to an end, but not just yet. S3 and its board partners are busy qualifying the final board design, as well as working on the graphics drivers, but S3 recently supplied us with an engineering sample of a prototype S8 board and an early video driver.
Before we get into the image quality analysis and benchmarks though, we’ll quickly recap DeltaChrome’s feature set and variants. For more detailed discussion on both topics, please refer back to our DeltaChrome preview from January 2003, and the DeltaChrome update from last September of this year.
DeltaChrome board and 9600 XT
Our DC board is an S8
Both cards run quite cool
For starters, DeltaChrome is not a RADEON 9800 XT killer. In fact, it would be very hard pressed to keep up with last year’s RADEON 9700 PRO. Since it’s limited to a 128-bit memory interface, it lacks the memory bandwidth to put up a proper fight. DeltaChrome’s micro-architecture is nothing to scoff at however. S3 actually goes beyond DirectX 9’s specs in some areas.
S3 starts DeltaChrome off with an eight-pixel pipeline architecture. Each pixel pipeline is outfitted with a single texture unit, just like ATI’s 8x1 configuration used on the RADEON 9700/9800. Also like ATI, DeltaChrome has four vertex shader units. S3 claims they’re able to cram all these features into a core that contains fewer transistors than RADEON 9800/9800 XT, but they won’t give us an exact figure other than to say it will be in the 60-80 million transistor range.
This helps to keep manufacturing costs in check, which is important since S3 will be primarily competing in the value and mainstream segments of the graphics market with DeltaChrome. To further ease production costs, DeltaChrome is built on TSMC’s 0.13-micron manufacturing process, just like many of NVIDIA and ATI’s latest products are.
Like the other DX9 cards on the market, DeltaChrome supports floating-point data formats. This is important for handling all sorts of complicated math. What does this mean to the end user? Scenes with more color ranges are possible without running into problems like color banding, creating a final image with more vibrant, lifelike colors.
DeltaChrome supports 128-bit vertex precision (32-bit floating point) while pixel precision is 96-bit (24-bit floating point). A lot has been made about NVIDIA’s decision to offer 128-bit precision in both. NVIDIA argues this gives them more flexibility than ATI (and now, S3 which boasts similar capabilities in this regard) but it remains to be seen if 128-bit precision is even feasible with today’s latest DX9 cards – the performance impact going from 24-bit (FP24) to 32-bit (FP32) may not be worth the increased precision.
In addition, many developers tend to stick with Microsoft’s minimum specifications in order to appeal to the widest audience possible. Right now the minimum precision called for by Microsoft that meets full precision requirements is 24-bit. NVIDIA’s performance mode, FP16, is considered half precision.