It is critical that systems with high-end graphics cards, such as the GeForce 6800 Ultra and GeForce 7800 GTX, are matched with an adequate power supply to ensure stable operation. Therefore, I have provided the following power supply information, which originated from NVIDIA's GeForce 7800 GTX GPU Reviewer's Guide:

The GeForce 7800 GTX requires a stable, 12-volt power source for best performance, reliability, and enjoyment. Many PC power supplies dedicate most of their 12-volt power to the power rail that goes to the CPU, rather than the peripheral connectors. Many power supplies also do not provide ample overload protection to protect system components such as motherboards and graphics cards.

For a SINGLE GeForce 7800 GTX graphics card, NVIDIA recommends a power supply with at least 350W, 22amps on 12V. For a DUAL SLI GeForce 7800 GTX graphics configuration, NVIDIA recommends a power supply with at least 500W, 30 amps on 12V. A list of SLI-certified power supplies can be found at SLIzone. Due to power distribution limitations of the PCI Express bus, GeForce 7800 GTX boards require a separate PCI Express power plug on the back end of the card.

System Specifications

• AMD Athlon 64 4000+ Processor
• Asus A8N-SLI Deluxe Motherboard
• Corsair XMS 3200 Memory Model 3200LLPRO - (2) 512MB DIMMs - 1GB Total
• Western Digital Raptor 74GB HDD (1), 10000RPM, 4.5ms Avg Seek, 8MB Buffer, SATA
• Western Digital Caviar 80GB HDD (2), 7200RPM, 8.9ms Avg Seek, 8MB Buffer, ATA-100
• Enermax 535W Power Supply Model EG565P-VE (24P)
• Sony Multiscan E500 21-Inch CRT Monitor
• NVIDIA GeForce 7800 GTX PCI-Express Graphics Card - 256MB - 430MHz/1.20GHz
• NVIDIA GeForce 6800 GT PCI-Express Graphics Card in SLI - 256MB - 350MHz/1.00GHz
• NVIDIA ForceWare Graphics Driver Version 77.62
• NVIDIA nForce4 AMD Driver Package Version 6.53.02
• Vsync Disabled / 75Hz Refresh Rate / 70Hz at 1920x1440 / 60Hz at 2048x1536
• Windows XP Professional with Service Pack 2 / DirectX 9.0c

Game Benchmarks

• Doom 3 - v1.0.1282
• Far Cry - v1.31 (Build 1378)
• Half-Life 2 - v1.0.1.0
• Splinter Cell Chaos Theory - v1.03

Notes

• All applications tested were patched to their latest version with the exception of Doom 3.
• Fraps was used to capture the minimum frame rate in some benchmarks.
• The predefined multichip rendering mode as defined in the application profile was always used when running in SLI mode.

The GeForce 7800 GTX features gamma corrected antialiasing and the ability to antialias objects that are constructed using transparent textures, which is a popular technique to render trees, branches, grass, and chain link fences. Multisampling antialiasing does not affect these types of objects since they are embedded within a polygon while supersampling antialiasing has a limited effect on transparent textures. NVIDIA refers to their new antialiasing technique as transparent adaptive multisampling or transparent adaptive supersampling depending on the method selected in the driver control panel.

New Antialiasing Features

The following JavaScript applet demonstrates the effects of antialiasing (2X, 4X, and 8XS) and anisotropic filtering (8X), which are features available on the GeForce 7800 GTX to improve image quality. The applet also demonstrates the effects of new antialiasing features exclusive to the GeForce 7800 GTX, which consist of gamma corrected antialiasing and transparency adaptive antialiasing (via multisampling or supersampling).

The default image contains yellow and white numeric labels that indicate areas in the scene where image quality improves as a particular feature is enabled. The labels correspond to the links underneath the image, which contain a number in parenthesis next to each image quality enhancing feature. For example, the labels containing the number 1 illustrate areas in the scene that improved when texture filtering was changed from trilinear to 8X anisotropic. Labels numbered 3 indicate areas that improved when the level of antialiasing was increased from 2X to 4X (with anisotropic filtering remaining at 8X).

Clicking on a link under the image will download the corresponding image (~120KB) from the server, which will be saved in your browser cache. After all of the images have been downloaded and saved, you will be able to quickly switch between them using the links below the image to see the differences in image quality. As you switch between the images, the changes, some of which are subtle, will occur in the areas marked by the labels.

GeForce 7800 GTX Antialiasing Demonstration

Labeled Image with Trilinear Filtering and 8X AF (1)

8X AF with 2X AA (2) and 4X AA (3)

4X AA and 8X AF with Gamma Correct (4) and MS TT (5) or SS TT (6)

vs. 8XS AA vs. 8XS and SS TT

A significant portion of the time I worked on this preview was devoted to this image quality comparison. There was no doubt that it was necessary after having witnessed the benefits of supersampling transparency adaptive antialiasing!

Notice that the image quality did not change when multisampling transparency was enabled. In this case, it is due to the specific type of texture being used in Half-Life 2. Supersampling transparency however, was designed to operate on a broader range of transparent textures.

Transparent Adaptive Supersampling Performance

In Half-Life 2, the performance hit associated with gamma correction and transparent adaptive supersampling was minor. The following results were obtained at a resolution of 1280x960 with 4X AA and 8X AF enabled. The driver Image Setting was set to High Quality and the highest-quality graphics options were enabled via the in-game menu. Doom 3 was run at 1024x768 with 4X AA and 8X AF with High Quality settings.

Half-Life 2

• 3dnews_canal - from 97 to 93 fps
• at_c17_c12 - from 82 to 80 fps
• at_canals_08 - from 105 to 101 fps

There was no impact on performance in Doom 3, which indicates that the transparent adaptive algorithm applies antialiasing to the appropriate textures as needed.

Doom 3

• demo1 - from 91 to 91 fps

Next Page: Performance and Conclusion