NVIDIA GeForce GT 520MX vs NVIDIA GeForce GT 555M vs NVIDIA GeForce GT 550M

NVIDIA GeForce GT 520MX

NVIDIA GeForce GT 555M

The NVIDIA GeForce GT 555M is a fast middle class graphics card for laptops. Depending on the version, it is based on the GF108, GF116 or GF106 architecture with different shader counts, clock speeds and memory configurations. It stems from the Fermi generation and supports DirectX 11 and OpenGL 4.0.

Versions (From highest to lowest performance):

1. 144 cores 709MHz (GF106), 128Bit GDDR5, e.g. MSI GX780
2. 144 cores 590MHz (GF106), 192Bit DDR3, e.g. Dell XPS 17, Alienware M14x
3. 144 cores 590MHz (GF106), 128Bit DDR3, e.g. Schenker XMG A501 / A701 (Clevo W150HRM / W170HN)
4. 96 cores 753MHz (GF108), 128Bit GDDR5, e.g. Lenovo Y570p / Y560p
5. 144 cores 525 MHz (GF116), 128 Bit DDR3, e.g. Medion Akoya P6812

GF106 architecture

The GF106 core of the GTX 555M is related to the GF100 core of the GeFore GTX 480M and offers 192 shaders and a 192 Bit memory bus for GDDR5. The GT 555M offers only 144 shaders and in some variants and a smaller memory bus with DDR3. 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 been both shortened and considerably modified. In contrast to the GF100, which was designed for professional applications, these latter chips target the consumer market. They feature more shaders (3x16 instead of 2x16) and more texture units (8 instead of 4) and SFUs per streaming multi-processor (SM). Since 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 be utilized more efficiently and the performance per core can be improved.

However, it's worth noting that the performance of the GF106 can also be worse than the GF100 (and its predecessors) in worst case scenarios. The ECC memory protection, which is important for professional applications, was completely omitted and the FP64 hardware was shortened (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 of the Nvidia chip cannot be directly compared to AMD cores of the Radeon 5000 series (e.g. HD 5830).

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.

The GF114 and GF116 chips are slightly reworked chips that were introduced in 2011. Due to a changed transistor design, the clock rates were raised while maintaining more or less the same power consumption levels.

Performance

The performance of the GT 555M is highly dependent on the version of the card (see above). The 3DMark 06 performance, for example, ranges from 8857 points (Lenovo Ideapad Y570) to 13000 points (MSI GX780R). For all intents and purposes, the GT 555M in the Lenovo is therefore essentially a fast GeForce 550M. The average GT 555M (with 144 shaders) is positioned in the lower high end class and enables users to play demanding games in high settings at 1366x768. Only Metro 2033 had to be played in lower settings during our benchmark tests (see below).

Features

A feature of the GF104/106/108 chips is the support for Bitstream HD Audio (Blu-Ray) output via HDMI. Similar to the Radeon HD 5730, the GT 555M can transfer Dolby True HD and DTS-HD bitstream-wise without quality loss to a HiFi receiver.

The GT 555M offers PureVideo HD technology for video decoding. The included Video Processor 4 (VP4) supports feature set C and allows the GPU 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 GT 555M can be of help in general calculations. For example, the stream processor can encode videos considerably faster than can a modern CPU. Furthermore, physics calculations can be done by the GPU using PhysX if supported, such as in Mafia 2 or Metro 2033.

According to Nvidia, the GT 555M supports 3D Vision. 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 and when not in conjunction with Optimus.

The relatively high power consumption of the GeForce GT 555M suits it for larger laptops from 14-17". To save power, the card supports Optimus for automatic switching between the integrated graphics card from Intel and the Nvidia GPU. Even though the video card natively supports this feature, its implementation is fully dependent on the notebook manufacturer.

NVIDIA GeForce GT 550M

The NVIDIA GeForce GT 550M is a fast middle-class graphics card for laptops. It is based on the GF108 core, which is similar to certain GeForce 400M cards but with higher clock speeds. Therefore, features like PureVideo HD (VP4), 3DVision, HD Audio support and others are identical to the GT445M.