图形芯片硬碰硬
作者：
西岸
责任编辑：阚智
来源：
《电脑商情报》
时间：2003-07-26 00:00
关键字：
芯片 图形
Choosing a high-end graphics processor is a lot like choosing between a Ferrari and a Porsche: In both cases, the buyers will get a high-performance vehicle with all the bells and whistles they have come to expect. The differences that do exist matter only to hard-core enthusiasts, and even they might find it difficult to translate listed features into actual performance advantages.
In high-end graphics, the race is between Nvidia's (Nasdaq: NVDA) GeForce FX 5900 Ultra and ATI (Nasdaq: ATYT) Technologies' Radeon 9800 PRO. Both graphics processors offer top-of-the-line memory interfaces, advanced vertex and pixel shading features, and new shadowing techniques. Although Nvidia had a little manufacturing stumble with the 0.13 micron chip prior to launching the 5900, the company is again running neck and neck with ATI.
A buyer cannot go wrong with either chip, but there are some distinguishing features advanced users might want to be aware of.
Raw Power
Nvidia's GeForce FX 5900 wins the horsepower race in terms of sheer numbers: It offers 27.2 GB/sec of raw memory bandwidth, compared with 21.6 GB/sec of raw memory bandwidth for ATI's Radeon 9800. Raw memory bandwidth multiplies the bit width of the memory interface times the clock speed. But the number is only the theoretical peak bandwidth of the chip, so the speed attained can vary during actual use.
Utilization of the bandwidth -- depending on features like color compression -- is just as important as the raw numbers, Daniel Paranovsky, product marketing engineer at ATI Technologies, told NewsFactor. So the memory bandwidth number can be deceptive.
ATI has an advantage in terms of the amount of memory it can move, according to Rob Enderle, research fellow at Forrester Research. But the Nvidia chip moves memory faster. The two chips run neck and neck on benchmark tests, Enderle told NewsFactor, and the outcome often depends on who is running the test -- not on the graphics processor.
"I honestly don't see the difference," Enderle said. "Unless you're running benchmarks, you won't see the difference."
Bit Benchmarks
One of the contrasts between the two chips is the architectural difference in how they handle instructions from the Direct X 9 application programming interface, the API that many future games will use. The Radeon chip from ATI employs a 24-bit shader engine, while the Nvidia GeForce chip employs a dual-function shader engine that operates at 16 bits or 32 bits.
The DirectX 9 benchmarking tests use 24 bit. ATI's Radeon 9800 usually comes out on top, because if the Nvidia chip is set to 32 bit it requires more processing time. If the Nvidia chip is set to 16 bit, it runs faster -- but the image quality suffers. "The difference between 16 bit and 24 bit [images] is pretty minor," Brian Burke, spokesperson for Nvidia, told NewsFactor.
Enthusiasts question the importance of such "synthetic" benchmarking tests, however. Most current computer games use DirectX 8.1 or 8.2, so only computer-game fans who want the latest and greatest will find the DirectX 9 performance difference important.
"Both technologies presuppose games that don't quite exist yet," Enderle said, in speaking of DirectX 9.
GeForce Advances
New features on the GeForce FX 5900 include Ultrashadow, which accelerates the drawing of shadows. This feature will be important for new upcoming games, such as Half Life 2 and Doom 3, Burke said. "These games rely on shadows to set a mood," he explained. "The quicker you can draw shadows, the better the experience."
Another feature, Intellisample HCT, provides better visual quality and antialiasing, due to more efficient compression of color, texture and "z" data. A "quality" mode enables anisotropic filtering, which improves the visual quality of surfaces seen from a sharp angle or from a distance.
The GeForce FX 5900 also enables advanced vertex and pixel shading effects and a unified driver architecture (UDA) that is backward and forward compatible. "One driver controls all of our products top to bottom," Burke said. "[The customer] won't have an orphaned product in two years."
"Nvidia has done a little bit better job with universal drivers," Enderle said.
There were some heat and noise concerns with GeForce FX 5800, but those have all but been eliminated, Enderle said. The Nvidia card is still considered the louder of the two cards, however. It also takes up a larger footprint due to its cooling system and may block an adjacent PCI slot on some computer systems.
Radeon Progresses
SmartShader, the Radeon 9800's DirectX 9 implemenation of vertex and pixel shaders, offers advanced features, such as higher-order surfaces, which make contours smoother and lighting effects more realistic; full floating point implementation that runs with no degradation in performance; and multiple render targets, which allow developers to create more complex effects with fewer passes of the shader engine, Paranovsky said.
"In terms of real-world gaming and the newer, shader-intensive titles typical of the next generation, such as WarCraft 3 and Unreal Tournament, we have a strong performance advantage," Paranovsky said.
The Radeon 9800 PRO also has an 8-pixel pipeline versus a 4-pixel pipeline for the GeForceFX 5900. That means the Radeon can calculate the color of twice as many pixels in a single clock cycle. The chip's Hyper Z III Plus technology optimizes the rendering of shadow volumes, and the chip's F-buffer enables developers to write OpenGL shaders of unlimited length. (OpenGL is an API that is popular in academia and workstations.)
Prices and Processors
There are factors outside the features-and-benefits realm that prospective buyers might want to consider. Because the two chips are "incredibly competitive" with each other, a user could base their decision solely on price, Enderle said. On CDW, the Radeon 9800 PRO add-in card sells for about US$400. The GeForceFX 5900 Ultra sells for about $499 at retailers, Burke said. A version with a slower clock speed sells for about $399.
Users allied with a particular microprocessor architecture might also want to consider that Nvidia has a stronger relationship with AMD (NYSE: AMD) , and ATI has a better relationship with Intel (Nasdaq: INTC) , Enderle said. In the past, many hard-core gamers were staunch AMD advocates, but the scales are beginning to balance, Enderle said.
Does a buyer go with the Ferrari or the Porsche? It many cases, it will be a coin flip. In other cases, only a line-by-line feature comparison and extensive testing will provide the answer. "For a lot of gaming enthusiasts," Paranovsky said, "the nuances between our products and theirs are important."
In high-end graphics, the race is between Nvidia's (Nasdaq: NVDA) GeForce FX 5900 Ultra and ATI (Nasdaq: ATYT) Technologies' Radeon 9800 PRO. Both graphics processors offer top-of-the-line memory interfaces, advanced vertex and pixel shading features, and new shadowing techniques. Although Nvidia had a little manufacturing stumble with the 0.13 micron chip prior to launching the 5900, the company is again running neck and neck with ATI.
A buyer cannot go wrong with either chip, but there are some distinguishing features advanced users might want to be aware of.
Raw Power
Nvidia's GeForce FX 5900 wins the horsepower race in terms of sheer numbers: It offers 27.2 GB/sec of raw memory bandwidth, compared with 21.6 GB/sec of raw memory bandwidth for ATI's Radeon 9800. Raw memory bandwidth multiplies the bit width of the memory interface times the clock speed. But the number is only the theoretical peak bandwidth of the chip, so the speed attained can vary during actual use.
Utilization of the bandwidth -- depending on features like color compression -- is just as important as the raw numbers, Daniel Paranovsky, product marketing engineer at ATI Technologies, told NewsFactor. So the memory bandwidth number can be deceptive.
ATI has an advantage in terms of the amount of memory it can move, according to Rob Enderle, research fellow at Forrester Research. But the Nvidia chip moves memory faster. The two chips run neck and neck on benchmark tests, Enderle told NewsFactor, and the outcome often depends on who is running the test -- not on the graphics processor.
"I honestly don't see the difference," Enderle said. "Unless you're running benchmarks, you won't see the difference."
Bit Benchmarks
One of the contrasts between the two chips is the architectural difference in how they handle instructions from the Direct X 9 application programming interface, the API that many future games will use. The Radeon chip from ATI employs a 24-bit shader engine, while the Nvidia GeForce chip employs a dual-function shader engine that operates at 16 bits or 32 bits.
The DirectX 9 benchmarking tests use 24 bit. ATI's Radeon 9800 usually comes out on top, because if the Nvidia chip is set to 32 bit it requires more processing time. If the Nvidia chip is set to 16 bit, it runs faster -- but the image quality suffers. "The difference between 16 bit and 24 bit [images] is pretty minor," Brian Burke, spokesperson for Nvidia, told NewsFactor.
Enthusiasts question the importance of such "synthetic" benchmarking tests, however. Most current computer games use DirectX 8.1 or 8.2, so only computer-game fans who want the latest and greatest will find the DirectX 9 performance difference important.
"Both technologies presuppose games that don't quite exist yet," Enderle said, in speaking of DirectX 9.
GeForce Advances
New features on the GeForce FX 5900 include Ultrashadow, which accelerates the drawing of shadows. This feature will be important for new upcoming games, such as Half Life 2 and Doom 3, Burke said. "These games rely on shadows to set a mood," he explained. "The quicker you can draw shadows, the better the experience."
Another feature, Intellisample HCT, provides better visual quality and antialiasing, due to more efficient compression of color, texture and "z" data. A "quality" mode enables anisotropic filtering, which improves the visual quality of surfaces seen from a sharp angle or from a distance.
The GeForce FX 5900 also enables advanced vertex and pixel shading effects and a unified driver architecture (UDA) that is backward and forward compatible. "One driver controls all of our products top to bottom," Burke said. "[The customer] won't have an orphaned product in two years."
"Nvidia has done a little bit better job with universal drivers," Enderle said.
There were some heat and noise concerns with GeForce FX 5800, but those have all but been eliminated, Enderle said. The Nvidia card is still considered the louder of the two cards, however. It also takes up a larger footprint due to its cooling system and may block an adjacent PCI slot on some computer systems.
Radeon Progresses
SmartShader, the Radeon 9800's DirectX 9 implemenation of vertex and pixel shaders, offers advanced features, such as higher-order surfaces, which make contours smoother and lighting effects more realistic; full floating point implementation that runs with no degradation in performance; and multiple render targets, which allow developers to create more complex effects with fewer passes of the shader engine, Paranovsky said.
"In terms of real-world gaming and the newer, shader-intensive titles typical of the next generation, such as WarCraft 3 and Unreal Tournament, we have a strong performance advantage," Paranovsky said.
The Radeon 9800 PRO also has an 8-pixel pipeline versus a 4-pixel pipeline for the GeForceFX 5900. That means the Radeon can calculate the color of twice as many pixels in a single clock cycle. The chip's Hyper Z III Plus technology optimizes the rendering of shadow volumes, and the chip's F-buffer enables developers to write OpenGL shaders of unlimited length. (OpenGL is an API that is popular in academia and workstations.)
Prices and Processors
There are factors outside the features-and-benefits realm that prospective buyers might want to consider. Because the two chips are "incredibly competitive" with each other, a user could base their decision solely on price, Enderle said. On CDW, the Radeon 9800 PRO add-in card sells for about US$400. The GeForceFX 5900 Ultra sells for about $499 at retailers, Burke said. A version with a slower clock speed sells for about $399.
Users allied with a particular microprocessor architecture might also want to consider that Nvidia has a stronger relationship with AMD (NYSE: AMD) , and ATI has a better relationship with Intel (Nasdaq: INTC) , Enderle said. In the past, many hard-core gamers were staunch AMD advocates, but the scales are beginning to balance, Enderle said.
Does a buyer go with the Ferrari or the Porsche? It many cases, it will be a coin flip. In other cases, only a line-by-line feature comparison and extensive testing will provide the answer. "For a lot of gaming enthusiasts," Paranovsky said, "the nuances between our products and theirs are important."
