NVIDIA GeForce 9800M GT SLI vs NVIDIA GeForce 9800M GTX

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 GTX

The Nvidia GeForce 9800M GTX is a graphics adapter for laptops based on the G92 core. In general, the GPU is similar to that of the 8800M GTX but with 112 unified shader cores instead of 96. The chip is manufactured in a 65nm process and because of the high shader count, the power consumption (75 Watt of the MXM board) can be quite high. As a result, the 9800M GTX is only found in larger laptops with relatively powerful cooling solutions.

The performance of the chip is noticeably better than both the 9800M GT and GTS because of the additional shader units (see benchmarks below). Therefore, DirectX 10 games of 2008 should all be playable in high details.

As with all cards with DirectX 10 capabilities, the GeForce 9800M GTX renders 3D images using "Unified Shaders". Dedicated pixel- and vertex shaders have been dropped in favor of stream processors, which have now taken up much of the rendering burden. Furthermore, the shader units are higher clocked than the core chip itself at 1250 MHz.

A feature found in the GeForce 9000 series is the integrated PureVideo HD video processor. The GPU is able to assist the CPU in the decoding of H.264-, VC-1-, MPEG2- and WMV9 video material.

In conjunction with the Nvidia 9100M G integrated graphics, the 9800M GTX supports Hybrid-SLI known as HybridPower. HybridPower is a technique available only in Windows Vista that allows users to choose between the integrated or dedicated graphics core for power-saving purposes. Eventually, graphics switching was seamlessly accomplished through drivers by Nvidia, a technology now known as Optimus. GeForceBoost is not supported with the 9800M GTX as there would be no performance gain when paired the integrated GPU.

Compared to desktop graphics cards, the 9800M GTX should be a bit slower than the GeForce 8800 GT, which has a higher memory clock rate.

The 9800M GTX was eventually succeeded by the GTX 260M. The latter is based off of the G92b core architecture and is produced in a 55nm fabrication process, leading to lower energy demands and heat dissipation.