NVIDIA GeForce GTX 485M SLI vs NVIDIA GeForce GTX 485M

Other than the GeForce GTX 480M, the 485M is no longer based on a trimmed down GF100 chip, but on the related GF104 instead. The GF104 is designed for the consumer sector and has a total of 384 cores. A number of cores may be disabled, for example the 470M with only 288 active cores.

The technology of the GF104 differs quite a bit from the GF100 chip (which was actually designed for professional use). The GF104 has more shaders (3x16 vs. 2x16), texture units (8 vs. 4) and SFUs (Special-Funciton-Units) per Streaming-Multiprocessors (SM). Nvidia now uses the superscalar architecture as there are still only two warp schedulers supporting three shader blocks. In theory, this helps to utilize the shaders more efficiently and increases the performance per core.

However, in the worst case, the performance can drop below the GF100 architecture (and its predecessors). The ECC memory protection, important in professional applications, was completely omitted and the FP64 was trimmed down (only 1/3 of the shaders are FP64-capable, only 1/12 of the FP32 performance). Because of these reductions in the GF104, the size of a SM increased only by 25% despite the higher number of shaders.

Note that it is not possible to directly compare the number of cores to the AMD Radeon graphics cards (e.g. HD 5870) or even to Nvidia's own predecessors (e.g., G92b), because shader architecture and clock rates are significantly different in the GF104 chip.

Performance

In our extensive test of the GeForce GTX 485M, we found that the GTX485M is significantly faster than the old GeForce GTX 480M (at the same TDP rating). The performance is on a level with two GeForce GTX 460M in SLI mode. Nearly all games are therefore playable in highest details and resolutions. Even demanding games like Mafia 2 or Battlefield Bad Company 2 can run fluently in 1080p with maximus detail settings. Detailed benchmarks can be found at the end of this page.

Features

What's new compared to the GF100 is support for Bitstream transfer of HD Audio (Blu-Ray) via HDMI in the GF104 chips. Similar to the HD 5850, the GTX 485M can transmit Dolby True HD and DTS-HD via Bitstream to compatible receivers without quality loss.

For decoding HD videos, the GTX485M supports PureVideo HD. The built-in Processor 4 (VP4) handles Feature Set C. As a result, MPEG-1, MPEG-2, MPEG-4 Part 2 (MPEG-4 ASP - z.B. DivX or Xvid), VC-1/WMV9 and H.264 can be fully decoded by the graphics card (VLD, IDCT, Motion Compensation, and Deblocking). Furthermore, two streams can be simultaneously decoded in realtime, e.g. Blu-Ray Picture-in-Picture (2x1080p lt DXVAChecker). In addition, PureVideo HD indicates HDCP encoding for digital interfaces.

The shader cores (also called CUDA cores) can also be used for general computations (e.g. Video Transcoding) by using the interfaces CUDA, DirectCompute 2.1 or OpenCL. Thanks to PhysX, the 485M can also perform physics calculations.

According to Nvidia, the support for 3D Vision includes support for the recent HDMI 1.4a standard as well. If enabled by the laptop manufacturer, content such as 3D games, 3D web streaming videos, 3D pictures and 3D Blu-Ray videos can be displayed on a 3D-capable TV (via discrete 3DTV Play) or on the internal notebook 3D display.

With regards to energy demand, the GTX 485M should be on par with the GeForce GTX 480M. In other words, both graphics cards should draw about 100 Watts each when including their respective memory and MXM boards. Due to the higher performance from the 485M, the performance/power efficiency here has clearly been improved.

Compared to desktop graphics cards, the performance of the 485M should be on par with a GeForce GTX 460 768MB which features less cores but operates on higher clock rates.