NVIDIA GeForce GTX 485M SLI vs NVIDIA GeForce GTX 460M vs NVIDIA GeForce GTX 480M

The NVIDIA GeForce GTX 460M is a high-end laptop graphics card released in 2010. It is based on the GF106 core as part of the Fermi architecture. As a result, the GPU supports DirectX 11 and OpenGL 4.0. In contrast to the GT 445M, which only features 144 core, the GTX 460M offers all the 192 shader cores of the GF106. The faster GTX 470M is based on the GF104 and offers even more shader cores at 288.

GF106 architecture

The GF106 core of the GTX 460M is related to the GF100 core of the GeFore GTX 480M and offers 192 shaders and a 192 Bit memory bus for GDDR5. Except for the memory controllers, the GF106 can basically be considered a halved GF104. Therefore, the architecture is not comparable to the old GT215 (e.g., GeForce GTS 350M) or GT216 (e.g., GeForce GT 330M) cores. Unlike the GF100, the smaller GF104, GF106, and GF108 cores have not only been reduced in size, but have also been considerably modified. In contrast to the GF100, which was designed for professional applications, these chips target the consumer market. They feature more shaders (3x16 instead of 2x16), more texture units (8 instead of 4) and SFUs per streaming multi-processor (SM). As there are still only 2 warp schedulers (versus 3 shader groups), Nvidia now uses superscalar execution to use the higher amount of shaders per SM more efficiently. In theory, the shaders can thereby be utilized more effectively and the performance per core can be improved. 

However, in worst case scenarios the performance can also be worse than of the GF100 and its predecessors. The ECC memory protection, which is important for professional applications, was completely omitted and the FP64 hardware shortened (only 1/3 of the shader are FP64-capable and therewith only 1/12 of the FP32’s performance). Because of these cutbacks, the size of the SM  grew only by 25% despite the higher number of shaders and larger warp schedulers with superscalar dispatch capabilities. Due to the different shader architectures and the higher clock rate of the shader domain, the core count of the GTX 460M cannot be directly compared to AMD cores of the Radeon 5000 series (e.g. HD 5850).

Detailed information on the GF104 architecture (and by extension also the GF106 and GF108) can be found in the desktop GTX 460 article by Anandtech.

Performance

Because the GeForce GTX 460M features a new architecture, the performance is not comparable to older chips with a similar core count. In contrast to the Radeon HD 5850, which could optionally use DDR3 memory, the 192 Bit memory bus of the GTX 460M is combined with GDDR5. Furthermore, the Fermi based chips offer a higher Tessellation performance than DX11 chips of the Radeon HD 5000 series.

We ran a set of benchmarks on an early pre-sample of a Toshiba Qosmio X500 with a 740QM CPU. In the synthetic benchmarks, the GTX 460M was on par with the DDR3 based Mobility Radeon HD 5850. In actual game benchmarks and tests, the performance was better than a HD 5850 with GDDR5 on average. In some cases (e.g., Unigine Heaven 2.1 and Dirt 2 Demo), the card even beat a Mobility Radeon HD 5870. On average, the GTX 480M was about 8-18% faster. The detailed benchmark and gaming results (including charts) can be found below.

Features

A novelty of the GF104/106/108 chips is the support for Bitstream HD Audio (Blu-Ray) output via HDMI. Similar to the Radeon HD 5850, the GTX 460M can transfer Dolby True HD and DTS-HD bitstream without quality loss to a HiFi receiver.

The GTX460M offers PureVideo HD technology for video decoding. The included Video Processor 4 (VP4) supports feature set C and therefore the GPU is able to fully decode MPEG-1, MPEG-2, MPEG-4 Part 2 (MPEG-4 ASP - e.g., DivX or Xvid), VC-1/WMV9, and H.264 (VLD, IDCT, Motion Compensation, and Deblocking). The X500 notebook tester was able to decode the VC-1 encoded Elephants Dream video with about 3-6% CPU load (according to the task manager). The H.264 coded Big Buck Bunny video was played back with 1-3% CPU load (both 1080p videos).

Furthermore, the GPU is able to decode two 1080p streams simultaneously (e.g., for Blu-Ray Picture-in-Picture).

Through CUDA, OpenCL, and DirectCompute 2.1 support, the GeForce GTX 460M can be of use in general calculations. For example, the stream processor can encode videos considerably faster than can many modern CPUs. Furthermore, physics calculations can be done by the GPU using PhysX if supported (e.g., Mafia 2 or Metro 2033). For example, the X500’s GPU ran Fluidmark more than 3x faster than its CPU (36 versus 11 fps) in our tests.

According to Nvidia,  3D Vision is supported on the GTX graphics cards. It enables the laptop to send 3D content (3D games, 3D Web Streaming, 3D photos, 3D Blu-Rays) to a built-in 3D enabled screen or an external 3D TV if supported by the laptop manufacturer. 

Unofficially, the power consumption of the GeForce GTX 460M should be about 72 Watt (TDP including the MXM board and memory), which is about the level of the Mobility Radeon HD 5850 - 5870. If not under load, the chip is clocked at 50/100 MHz (chip/shader) and 200/400 in 2D mode and 3D mode, respectively, to save power. Furthermore, the 400M series supports Optimus to automatically switch between the integrated graphics card from Intel and the Nvidia GPU. However, its implementation is dependent on the manufacturer. As current (2010) quad-cores don’t house an integrated GPU, we won’t see many Optimus designs with a GTX 460M GPU before the launch of Sandy Bridge in 2011.

The similarly named desktop GeForce GTX 460 is based on the GF104 chip and offers more shader cores at 336. Therefore, it is significantly faster than the GTX 460M and even the GTX 470M.