NVIDIA GeForce 9800M GT SLI vs NVIDIA GeForce 9800M GS

NVIDIA GeForce 9800M GT SLI

The Nvidia GeForce 9800M GT is based on the G92 architecture and is essentially a reduced 9800M GTX chip with only 96 shaders instead of the usual 112 found on GTX chips. Like with the 8800M GTX, the chip is produced in a 65nm fabrication process and even share comparable specs. Since this is an SLI system, the amount of available shaders is doubled due to the use of two 9800M GT cards. Note, however, that the available memory is not doubled because the same content is stored onto each card.

Like all DirectX 10 graphic cards, the GeForce 9800M GT SLI contains "Unified Shader" cores, 2x96 stream processors to be exact. These cores take the place of dedicated pixel and vertex shaders and are even clocked higher than the core GPU itself.

Hybrid Power is a Windows Vista only option that allows switching between onboard graphics (with Nvidia chipset) and dedicated graphics cards, in this case the 9800M GT SLI. Therefore, the dedicated graphics card can be disabled at will for power-saving purposes. Future Nvidia cards are expected to allow automatic switching through drivers, now known as Optimus Technology. GeforceBoost does not work with the 9800M GT because the connection with the SLI chipset would not result in any increase in performance.

The performance increase of two 9800M GT cards in SLI mode is between 0% and 40% over a single 9800M GT, depending on the application. For current DirectX 10 games such as Crysis, World in Conflict, Bioshock or Age of Conan, the performance of dual 9800M GT cards should be sufficient for smooth play at high levels of detail.

The phenomenon known as micro stuttering can occur in all SLI systems, including this 9800M GT SLI setup. The user may experience stutterings despite average frame rates of around 30fps. See here for more information on micro stuttering.

A hardware feature of the GeForce 9000 series is the integrated PureVideo HD video decoder. This allows the GPU to aid the CPU in decoding H.264-, VC-1-, MPEG2- or WMV9 video files.

The high current consumption of up to 130 Watt (when including both the VRAM and MXM board) means that the 9800M GT SLI is reserved for large and heavy laptops with sufficient cooling only. Therefore, the 9800M SLI series can only be found in big and heavy laptops.

NVIDIA GeForce 9800M GS

The Nvidia GeForce 9800M GS is a graphics adapter for laptops and based on the G94 core with 64 shader processors. The chip is produced in 55nm (as the 1024 MB versions of the 9800M GTS and the GTS 160M). Because of the max. 512 MB GDDR3 the TDP is lower (60 Watt) than the 9800M GTS (512 and 1024 MB version: 75W).

Because of the additional shaders but lower clock speed than the GTS, the 9800M GS is between the 9700M GTS and 9800M GTS. Therefore, DirectX 10 games of 2008 should all be playable in medium to high details.

As all cards with DirectX 10 capabilities, the GeForce 9800M GS renders the 3D images using "Unified Shaders". There don't exist any more dedicated pixel- and vertex shaders but 64 so called stream processors make the graphic work (which has been done by pixel and vertex shaders in former days). Furthermore, the shader units are higher clocked than the chip.

An advantage of the GeForce 9000 series is the integrated PureVideo HD video processor. It is able to help with the decoding of H.264-, VC-1-, MPEG2- and WMV9 video material in HD quality and eases the CPU.

In conjunction with the Nvidia 9100M G integrated graphics, the 9800M GS supports Hybrid-SLI (only HybridPower). HybridPower is a technique to choose between the integrated and dedicated graphics core, if performance or battery runtime is needed. This works only in Windows Vista. Up to now the user has to use a tool to switch between the GPUs. Later Nvidia wants to switch automatically in the drivers. GeForceBoost is not supported with this card, as there would be no performance gain to combine the integrated GPU with the 9800M GS.

Compared to desktop graphics cards, the 9800M GS should be a bit slower than the GeForce 9600M GT.