Today, NVIDIA will be announcing the availability of their next-generation GeForce 7800 GTX graphics processing unit (GPU). The GeForce 7800 GTX is based on the PCI-Express interface and is replacing the popular GeForce 6800 Ultra at the high-end. With NVIDIA's Scalable Link Interface (SLI) technology, a second GeForce 7800 GTX can easily be added to a system in order to achieve an unprecedented level of 3D graphics performance.
GeForce 7800 GTX Logo
The GeForce 7800 GTX will be available to order today from online retailers, system builders, and PC OEMs and carries a suggested retail price of $599. The following PriceGrabber search will provide a list of online retailers that are selling the GeForce 7800 GTX. Keep in mind that the price of a product is typically determined by supply and demand. One of the main reasons for the $599 price tag is that the PCI-Express versions of the GeForce 6800 Ultra and GeForce 6800 Ultra have retained much of their original value due to the tremendous popularity of SLI.
Today may also mark the end of era an NVIDIA did not provide information in regards to an AGP version of the GeForce 7800 GTX. They are also announcing the GeForce 7800 GTX today and declined to provide any further information at this time concerning additional GPUs that are expected to make up the GeForce 7 Series.
Reference GeForce 7800 GTX
Click Image to Enlarge
The reference card from NVIDIA arrived last Thursday and work began on a preview the following day. Although five days is not an adequate amount of time to judge a product as complex as the GeForce 7800 GTX, first impressions will have to suffice for now. After all, the GeForce 7800 GTX contains a record-breaking 302 million transistors!
This preview, like many others, is unique. Once the reference card is installed and testing begins, any number of events can take place that will determine the path a reviewer takes. After running a series of initial benchmarks using Half-Life 2, I knew that the GeForce 7800 GTX was going to deliver blistering performance. I was somewhat concerned beforehand as I contemplated how well the GeForce 7800 GTX would match up against the GeForce 6800 GT SLI setup I have been using for the past few months. Following the initial benchmark results from Half-Life 2, I decided to devote more time to an image quality investigation.
Reference GeForce 7800 GTX
Click Image to Enlarge
Before the GeForce 6 Series was launched, NVIDIA was studying shader programs that developers were writing for their games. Over 1,300 shader programs were examined and the results assisted engineers in the design of the shader architecture of the GeForce 7800 GTX. One of their findings was that developers were ready to embrace advanced techniques that enhance the gaming experience through improved visual quality. Once such example is shown below in Splinter Cell: Chaos Theory, which supports High Definition Rendering (HDR) through Shader Model 3.0 - a feature that is currently exclusive to NVIDIA's GeForce 6 Series GPUs and the new GeForce 7800 GTX.
Performance of the GeForce FX sometimes dropped when a Pixel Shader 1.x shader was executed compared to executing a similar shader under Pixel Shader 2.0. Will the GeForce 6800 have a similar performance drop when executing a shader using Pixel Shader 3.0?
Actually it will be the opposite. I think there is a bit of confusion about Shader Model 3.0 and Shader Model 2.0. While Shader Model 3.0 will enable some "new" effects, it is better characterized by ease of programming, more efficient use of the hardware, and higher scene complexity/or frame rates. Shader Model 3.0 makes developers lives easier due to the support for advanced programming features such as loops and branches.
This is a fundamental requirement and will improve the efficiency in how programmers can write their code. Without support for loops and branches enabled by Shader Model 3.0, developers will be forced to break up longer Shader Model 3.0 shader programs into smaller segments that will run on Shader Model 2.0 hardware. This will absorb clock cycles which will hamper performance in games that use the latest version of DirectX and have more sophisticated Shader Model 3.0 pixel shaders.
It is important to note that in some cases, developers can create the same effect with Shader Model 2.0 and Shader Model 3.0, however it may take longer to program using Shader Model 2.0 and may require more passes through the hardware to render.
Shader Model 3.0 does introduce some new functionality - particularly dynamic branching in the pixel shader, which must be used carefully for good performance. But in general, Shader Model 3.0 should actually make development easier, and can offer some nice performance benefits for complex shaders that can be executed in pixel shader 2.0, but can be executed more efficiently in Shader Model 3.0.
A summary of the GeForce 7800 GTX specifications and features is presented in the following tables. The recent performance growth-rate of high-end GPUs is causing many new games to become CPU limited. An indication that a game is CPU limited occurs when graphics settings, such as antialiasing or resolution, are increased and the difference in performance is minor. In this case, program optimizations or a faster CPU would be needed to achieve greater performance. GPUs typically become a bottleneck during situations where a very high fill-rate is required, such as high levels of antialiasing at high resolutions or when a less powerful GPU is paired with a fast CPU.
Vertex shader processing efficiency has improved as a multiply and accumulate (MADD) operation in the vector processing unit is now accomplished in a single clock cycle. MADD operations are prevalent in many graphics operations such as transformation and lighting. Further enhancements are found in the performance of scalar operations, such as matrix operations, which have improved by 20-30% over the NV4x.
Vertex Shader Specifications
The GeForce 7800 GTX can process 8 floating-point MADD operations per pixel compared to 4 on the GeForce 6800 Ultra.