NVIDIA GeForce GTX 485M vs NVIDIA GeForce GTX 470M

NVIDIA GeForce GTX 485M

The Nvidia GeForce GTX 485M is the fastest graphics card for laptops at the time of announcement (Q1 2011). It is based on the GF104 chip and offers all 384 shader cores and the full 256 Bit memory bus. Due to the high clock rate of 575 MHz, it is significantly faster than the old GeForce GTX 480M of which it replaces. It also supports DirectX 11 and OpenGL 4.0.

NVIDIA GeForce GTX 470M

The NVIDIA GeForce GTX 470M is a high-end laptop graphics card introduced in 2010. It is based on the GF104 core as part of the Fermi architecture (as opposed to the GF100 core that the faster GTX 480M is based off of). As a result, the GTX 470M supports both DirectX 11 and OpenGL 4.0.

GF104 architecture

The GF104 core of the GTX 470M is related to the GF100 core of the GeFore GTX 480M and offers 384 shaders and a 256 Bit memory bus for GDDR5. The GTX 470M, however, offers only 288 cores of the 384 and a 192 Bit memory bus. The architecture of the GF104 is not comparable to the old GT215 (e.g., GeForce GTS 350M) or G92b (e.g., GeForce GTX 285M) cores.  Unlike the GF100, the smaller GF104, GF106, and GF108 cores were not only reduced in size, but also 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 efficiently and the performance per core is improved.

However, in worst case scenarios the performance of the GTX 470M 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 reduced (only 1/3 of the shader are FP64-capable and thereby 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 can not be directly compared to AMD cores of the Radeon 5000 series (e.g. HD 5850).

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

Performance

Because the GeForce GTX 470M 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 470M is combined with GDDR5. Furthermore, the Fermi-based chips offer higher Tessellation performance than DX11 chips of the Radeon HD 5000 series. The performance of the GTX470M should also be a bit above the Mobility Radeon HD 5870 and first tests even show performance scores above a GTX 480M. Therefore, all modern games of 2010 (except Metro 2033 and Crysis) should run in highest detail settings fluently.

Features

A novel feature 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 470M can transfer Dolby True HD and DTS-HD bitstream-wise without quality loss to a HiFi receiver.

The GTX 470M 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).

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 470M 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).

According to Nvidia, support for 3D Vision on the GTX graphics cards is also enabled. 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 470M should be at about 75 Watt (TDP including the MXM board and memory), which is about the level of the Mobility Radeon HD 5870. Without load, the chip is clocked at 50/100 MHz (chip/shader) and 200/400 MHz 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, whether or not this feature is included on a notebook will be dependent on the notebook manufacturer. As modern quad cores (2010) don’t house an integrated GPU, we won’t see many Optimus designs with GTX 470M before the launch of Sandy Bridge in 2011.

The similarly named desktop GeForce GTX 470 is based on the GF100 chip and offers 448 shader cores. Therefore, it is significantly faster than a GTX 470M.  Instead, a more comparable desktop GPU to the GTX 470M in terms of overall performance would be the GeForce GTS 450.