NVIDIA nForce 790i SLI Ultra and GeForce 9800 GX2

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Enter the GeForce 9800 GX2

As we mentioned earlier, the second new addition to NVIDIA's ultimate gaming platform is the GeForce 9800 GX2.  Although this is the first product to be released in the GeForce 9800 series, it is not based on a brand new GPU.  The GeForce 9800 GX2 is built around NVIDIA's proven G92 GPU, that first debuted on the GeForce 8800 GT.  On the GeForce 9800 GX2, however, all of the GPU's stream processors (128) are exposed, just like on the GeForce 8800 GTS 512MB.  With two GPUs powering the board, that means it has a total 256 stream processors at its disposal, in addition to 1GB of DDR3 memory - 512MB per GPU.

Due to the fact that the GeForce 9800 GX2 is built around an existing GPU, we won't delve deeply in to the GPU architecture.  We've covered the G92 and detailed its features a few previous articles, so we won't do it again here.  If you'd like to read more about the GPU specifically, we recommend perusing these three previous HotHardware articles:

NVIDIA GeForce 9800 GX2
Features and Specifications
Fabrication Process  65nm
Total Number of Transistors  1010 milltion
Core Clock (Including dispatch, texture units, and ROP units)  600MHz
Shader Clock (Stream Processors)  1500MHz
Processor Cores  256
Memory Clock (Clock Rate / Date Rate)  1000MHz / 2000MHz
Memory Interface  256-bit
Total Memory Bandwidth  128GB/s
Total Video Memory  1024MB
ROPs  32
Texture Filtering Units  128
Texture Filtering Rate  76.8 GigaTexels/sec
HDCP Support  Yes
HDMI Support  Yes
Connectors  2 x Dual-Link DVI-I, 1 x HDMI
Bus Technology  PCI Express 2.0
Form Factor  Dual Slot
Power Connectors  1 x 6-Pin, 1 x 8-Pin
Max Board Power   197 Watts
GPU Thermal Threshold  105ºC

The main features and specifications for the GeForce 9800 GX2 are listed above.  As you can see, the GPU is built using a 65nm fabrication process.  On stock GeForce 9800 GX2 cards, the GPUs are clocked at 600MHz, with a 1.5GHz shader clock, and 1GHz memory.  If you recall, the GeForce 8800 GTS 512MB's GPU is clocked at 670MHz with 900MHz memory, so a pair of GTS cards running in SLI mode will offer higher shader performance and fillrate, but less memory bandwidth.  Keep that in mind as  you look through the benchmark results that appear a little later in this article.

The GeForce 9800 GX2 offers a total of 128GB/s of memory bandwidth, with a 1GB frame buffer (512MB per GPU), 32 ROPs (16 per GPU), and  128 Texture Filtering Units (64 per GPU), for a total of 76.8GigaTexels/sec.

Not listed here are some new PureVideo HD related features that have been exposed in the G9x series of GPUs.  In addition to all of the previous PureVideo HD related features available on other GeForce graphics cards, the 9800 GX2 has support for Dynamic Contrast Enhancement, Dynamic Color Enhancement, and Dual-Stream Decode.  If you've ever corrected a digital photo's color and contrast in a program like Photoshop,  you'll be familiar with how the Dynamic Color and Contrast Enhancements work.  Each frame in a digital video is "corrected" to adjust for poor quality recording or mastering.  And the Dual-Stream Decode allows the GeForce 9800 GX2 to accelerate two video streams simultaneously, which helps reduce CPU utilization when playing back Blu-Ray or HD DVD disks that have PiP functionality.

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