NVIDIA GeForce GTX 260M SLI vs NVIDIA GeForce GTX 280M SLI

NVIDIA GeForce GTX 260M SLI

The Nvidia GeForce GTX 260M SLI is a combination of two Nvidia GeForce GTX 260M graphics cards for laptops linked together in SLI mode. The combination can be up to 40% faster than a single GTX 260M if given the proper game or driver support. In fact,some games may even run slower under SLI than with a single 260M if driver support is poor. Regardless, current consumption is twice as high as a single 260M. Notably, Nvidia drivers support the deactivation of SLI to save power. This is in contrast to the Catalyst drivers of the 4870 X2 at the time of our review.

The graphics memory of both cards can't be added and compared to single cards, as each card stores the same information. Therefore, a GTX 260M SLI with 2x512 graphics memory only counts as 512 MB for games.

As all SLI combinations, the GeForce 260M SLI may suffer from noticeable micro stuttering at frame rates between 20 to 30 fps. This is due to the inconsistent delays between subsequent frames being rendered and shown onscreen. As a result, an SLI combination may need higher frame rates for fluent gameplay.

Similar to other cards with DirectX 10 capabilities, the GeForce GTX 260M SLI combination renders 3D images using "Unified Shaders". Dedicated pixel shaders and vertex shaders have been dropped in favor of 2x112 stream processors for rendering graphic work that would have normally been done by specialized pixel and vertex shaders. Furthermore, the shader units are higher clocked than the chip at 1375 MHz.

The performance of the GTX 260M SLI is in the region of a single GTX 260M, but can be about 40 percent higher depending on application and driver support. A single GTX 260M is only a bit faster than a 9800M GTX due to the higher clock speed. For current DirectX 10 games like Crysis, World in Conflict, Bioshock or Age of Conan, the performance of this graphics card is sufficient with medium and high details. Older games and less demanding ones run fluently with high resolutions and full details. The memory component is up to 2x1024 MB GDDR3 with speeds up to 950MHz in MXM 3.0 boards or up to 800 MHz in MXM 2.0 boards.

An advantage of the GeForce GTX 260M SLI is the integrated PureVideo HD video processor. As a result, it is able to decode/encode H.264-, VC-1-, MPEG2- and WMV9 video material that would have otherwise been processed by the CPU. This ultimately allows the CPU to concentrate more on other tasks and programs simultaneously.

Both chips also support PhysX and CUDA applications. A single GTX 260M can also be used to calculate PhysX effects if supported by the game or application.

HybridPower is a technique to choose between the integrated (if available) and dedicated graphics core for power-saving purposes. So far, this works only in Windows Vista. Up to now, the user had to use a tool to switch between the GPUs. In the near future, Nvidia intends to be able to switch GPUs automatically in the drivers (now known as Optimus Technology, which is not supported by the GTX 260M SLI). GeForceBoost is not supported with this card as there would be no performance gain if one were to combine the integrated GPU with the dedicated 460M SLI.

The current consumption of up to 2x75 = 150 Watts (including the MXM board and VRAM) allows the use of the SLI cards only in laptops with a strong cooling system. Therefore, the GTX 260M SLI can be found only in heavier and larger desktop replacement (DTR) notebooks.

Compared with desktop graphics cards, the performance of the GTX 260M SLI is about on par with the GeForce 9800 GT SLI (600/1500/900).

NVIDIA GeForce GTX 280M SLI

The Nvidia GeForce GTX 280M SLI is a graphics solution that combines two Nvidia GeForce GTX 280M cards in an SLI setup. As not every game supports SLI efficiently, the performance increase compared to a single card is only about 0-40%. The most frequently used technique is Alternate Frame Rendering (AFR), where one card renders every odd frame while the second card renders every even frame. Due to the SLI setup, users may experience micro stuttering due to the irregular delays between sequential frames.

Each of the two GeForce GTX 280M is based on the G92b core and is produced in 55nm. It features the full 128 pipelines of the G92b and is therefore more comparable to the desktop 9800M GTX+ than the desktop GTX 280.

The Nvidia GeForce GTX 280M SLI is bundled with the GeForce 9400M G chipset (for laptops based on the Core 2 Duo) and therefore supports HybridPower if supported by the manufacturer. With HybridPower, both GTX cards can be disabled and only the chipset graphics core can run, leading to longer battery life (and possibly less fan noise). Modern Core i7 laptops use an Intel chipset and do not support HybridPower.

Since there are two GTX 280 cards active in SLI, the electric current consumption and exhumed heat are about twice as much as what a single GTX 280M can produce. Due to the large power and cooling requirements, this SLI combination is usually reserved for large desktop replacement (DTR) laptops (like the Alienware M17x).