NVIDIA GeForce GT 625M vs NVIDIA GeForce GT 635M

The NVIDIA GeForce GT 625M is an entry-level, DirectX 11 compatible graphics card that was announced in the third quarter of 2012 for laptops. Compared to the older GeForce GT 620M, it is a higher clocked version of the chip. The 620M can be based on either the 40nm GF108 chip (similar to the GeForce GT 525M) or the new power-optimized 28nm GF117 chip with 64-bit or 128-bit DDR3 memory. Both architectures still stem directly from the Fermi generation. Therefore, both versions are also possible for the GT 625M.

It should be noted that the 28nm version of the GT 620M does not offer dedicated graphics ports and can therefore only be used in conjunction with Optimus. 

Architecture

The GF117 is based on the optimized GF108 Fermi chip (GeForce GT 540M) and offers 96 shaders, 16 TMUs and 4 ROPs. Each shader core is clocked twice as fast as the rest of the graphics chip, a technique known as hot clocking. More detailed information on Fermi can be found on the GT 435M GPU page.

Performance

The performance of the GT 625M depends on the Turbo clock in the used laptop but should be on average a bit above the average GT 620M. Therefore, the card is suited for casual gamers as demanding games of 2012 may only run in low detail settings fluently.

Features

The shader cores (also called CUDA cores) can be used for general calculations with APIs such as CUDA, DirectCompute 2.1 and OpenCL. PhysX is theoretically possible, but the GT 625M is too slow to handle both PhysX and 3D rendering for modern games. 3D Vision is not supported according to Nvidia.

The NVIDIA GeForce GT 635M is a fast middle class graphics card for laptops and is essentially a renamed GeForce GT 555M. It is based on the GF108 or GF116 cores with different shader counts, clock speeds and memory configurations. It stems from the Fermi generation and supports DirectX 11 and OpenGL 4.0.

Versions (of the GT 555M):

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

Architecture

The GF114 and GF116 chips are slightly reworked architectures that were introduced in 2011. Due to a changed transistor design, the clock rates could be higher without increasing overall power consumption. Detailed information on the GF106 can be found on the GeForce GT 555M page and information on the GF104 on the GeForce GT 435M page.

Performance

The performance of the GeForce GT 635M is dependent on the version of the card used (see above). The performance range is similar to the former GT 555M and somewhat below the Kepler based GT 640M. Therefore, most modern games run fluently in medium to high settings in 1366x768. Only very demanding games like Metro 2033 or Battlefield 3 will require lower settings (see our benchmark tests below).

Features

A novelty of the GF104/106/108 chips is the support of Bitstream HD Audio (Blu-Ray) output via HDMI. Like the Radeon HD 5730, the GT 635M can transfer Dolby True HD and DTS-HD bitstream to a HiFi receiver without quality loss.

The GT 635M 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). This can free up processing time from the CPU, leading to better multitasking performance.

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 635M can be of help in general calculations. For example, the stream processor can encode videos considerably quicker 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 635M supports 3D Vision. It enables the laptop to output 3D content (3D games, 3D Web Streaming, 3D photos, 3D Blu-Rays) to a 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 635M suits it for larger laptops starting from 14-inches. To save power, the card supports Optimus to automatically switch between the integrated Intel graphics card and the Nvidia GPU. Even though the video card natively supports Optimus, it is up to the manufacturer to implement the technology.