Graphics Cards Guide
The NVIDIA GeForce 9800 GX2 1GB
The NVIDIA GeForce 9800 GX2 1GB
As the first member of NVIDIA's high-end GeForce 9800 series, the GX2 is also the first graphics product to feature the company's new Hybrid SLI technology. Hybrid SLI has two major components, GeForce Boost and HybridPower. The GeForce 9800 GX2 supports the latter part, HybridPower, which is basically about turning off the discrete graphics processor (in this case, the GX2) for less demanding applications and usage (like surfing the internet). Obviously then, some other device has to be producing the video output and in fact, HybridPower works only if the GX2 is paired with a compatible HybridPower motherboard that has an onboard GPU (such as the GeForce 8200 mGPU and nForce 780a for example). The onboard graphics will take over when the GX2 is powered down fully, potentially saving some energy and lowering heat/noise production. When a 3D application is started, the GX2 will be prodded to start earning its wages.
No doubt, it's an interesting take on energy efficiency though we have our doubts on whether enthusiasts that purchase the GeForce 9800 GX2 will be that concerned about power consumption in the first place. Of course, users will have the option to disable it. More extensive information about Hybrid SLI and its supporting components can be found in our previous coverage of this technology here.
Another aspect of the GeForce 9800 GX2 belonging to the GeForce 9 series is its support for the new PureVideo HD enhancements that have been mentioned before in our GeForce 9600 GT review. The GX2 will have support for all the features mentioned, like dual stream decode acceleration and dynamic contrast and color enhancements. From what we understand, these features are all present in the VP2 onboard the GX2 and enabled with the ForceWare 174 drivers.
Finally, for those thinking of investing in a pair of these GX2 cards, NVIDIA has tweaked the way it does Quad SLI. Formerly, a mixture of split and alternate frame rendering was used to maximize the four cores in a Quad SLI setup. According to NVIDIA, this method has its drawbacks when it came to modern games, which had more multi-pass rendering and inter-frame effects, thereby creating latency issues with this method. Hence, a new 4-way alternate frame (4-way AFR) technology is used for the GX2 and is claimed to provide better scaling. However, due to the limitations of a maximum of three extra frames buffering on Windows XP, this new feature will only be supported in Windows Vista which has no such limit.
Moving onto the physical graphics card itself, the GeForce 9800 GX2 is quite hefty, with a length similar to the GeForce 8800 GTX/Ultra series. The fan is mostly quiet and while there are quite a number of air vents dotting its shroud, the rear exhaust looks rather tiny and we aren't too sure of its effectiveness. Given its two G92 cores, it is understandably a power guzzler, with a maximum board power of 197W. For consumers, a 580W PSU is needed for a single GX2 and 850W PSU for Quad SLI. You'll also need both 8-pin and 6-pin PCIe connectors, so you'll need the latest PSUs as well. During installation, we ran into some issues with one of our PSU units (ironically, it was a unit sent by NVIDIA for testing the GX2) where the 8-pin connector wouldn't fit properly due to the tight metal enclosure. At least NVIDIA had LED visual indicators that showed if the connectors were not attached properly.
The GeForce 9800 GX2 is also the first reference board from NVIDIA to feature a HDMI output, with the audio stream jacked in via S/PDIF headers found on the card. This has been seen in the Geforce 9600 GT and we expect vendors to have the necessary cables and instructions for the retail GeForce 9800 GX2. Of the two DVI ports though, only the one beside the HDMI port is bootable. The HDMI port itself is bootable too.