NVIDIA GeForce GT 755M SLI vs NVIDIA GeForce GT 740M

NVIDIA GeForce GT 755M SLI

The NVIDIA GeForce GT 755M SLI is a high-end DirectX 11-compatible graphics solution for laptops, consisting of two GeForce GT 755M. Each card has a 28nm GK107 core based on the Kepler architecture. With SLI, each card usually renders a single frame (AFR mode). Therefore, it may suffer from micro stuttering in low fps ranges of 30fps. This happens because of different timespans between two frames (e.g. irregular delays between sequential frames).

Compared to the GeForce 750M, the 755M respectively 755M SLI is combined only with GDDR5 graphics memory and clocked slightly higher.

Architecture

The GK107 Kepler core offers two shader blocks, called SMX, each with 192 shaders for a total of 384 shader cores that are clocked at the same speed as the processor core. Although more shader cores are available in the Kepler architecture as compared to the Fermi design, the Kepler shaders are expected to be up to two times more power efficient. However, due to the missing hot clock of the shader domain, two shaders of a Kepler chip are as fast as one shader of a Fermi chip, even though Fermi shaders are clocked at twice the speed.

PCIe 3.0 is now supported by the mobile Kepler series and GPU Boost 2.0 can automatically overclock the card if the laptop cooling system allows it. This feature is available on any notebook with a graphics card of the 700M series.

Performance

Thanks to the slighly higher clocks, the GT 755M SLI is somewhat faster than the former GT 750M SLI and performs similar to a single GeForce GTX 770M or GTX 680M. Depending on the game, there can be big differences here, depending on how well SLI scales in a particular case. Overall, most current games (as of 2013) can be played fluently in 1080p and (very) high settings.

Features

The feature set includes support for up to 4 active displays. Furthermore, high resolution monitors of up to 3840x2160 pixels can now be connected using DisplayPort 1.2 or HDMI 1.4a if available. HD-Audio codecs, such as Dolby TrueHD and DTS-HD, can be transmitted via bitstream mode through the HDMI port.

The 5th generation PureVideo HD video processor (VP5) (also integrated in the GK107 core) offers hardware decoding of HD videos. Common codecs such as MPEG-1/2, MPEG-4 ASP, H.264 and VC1/WMV9 are fully supported up to 4K resolutions while VC1 and MPEG-4 are supported up to 1080p. Two streams can be decoded in parallel for features such as Picture-in-Picture. Another feature is the inclusion of a dedicated video encoding engine similar to Intel QuickSync that can be accessed via the NVENCI API.

Power Consumption

The power consumption of the GeForce GT 755M SLI doubles compared to a single 755M, reaching about 100 W. As a result, the Nvidia GPU is only suited for larg gaming notebooks.

NVIDIA GeForce GT 740M

The NVIDIA GeForce GT 740M is a DirectX 11 graphics card of the middle class. It is based on the Kepler architecture and manufactured by TSMC in a 28-nanometer process. In addition to an older version with the GK107 chip (384 shader, 810 - 895 MHz, 128 bit memory), there also exist models with the new GK208 (384 shader, up to 980 MHz plus boost, 64 bit memory). Both versions usually use DDR3 memory; however, GDDR5 versions are possible, too.

Architecture

Both GK107 and GK208 are based on the Kepler architecture and offer two shader blocks, called SMX, each with 192 shaders for a total of 384 shader cores. The shaders are clocked at the same speed as the rest of the chip. Although more shader cores are available in the Kepler architecture as compared to the Fermi design, the Kepler shaders are much more efficient. However, due to the missing hot clock of the shader domain, two shaders of a Kepler chip are as fast as one shader of a Fermi chip even though Fermi shaders are clocked at twice the speed.

PCIe 3.0 is now supported by the mobile Kepler series and an optional Turbo mode can automatically overclock the card if the laptop cooling system allows it. This feature is available on any notebook with a graphics card of the 700M series.

Performance

The gaming performance of the GeForce GT 740M depends on the used chip. Our benchmarks with a GK107 version show a performance just 10 percent below the GT 650M. Current games (as of 2013) can thus be played in medium to high settings. In older titles, there are also reserves for additional quality features like AA and AF. The GK208 version, however, performs significantly worse and is sometimes even below the GT 640M. Still, the performance depends on the core clock and the GPU Boost 2.0. Detailed benchmarks can be found further down on this page.

Features

The feature set of the GT 740M corresponds to the GT 730M. This includes support for up to 4 active displays. Furthermore, high resolution monitors of up to 3840x2160 pixels can now be connected using DisplayPort 1.2 or HDMI 1.4a if available. HD-Audio codecs, such as Dolby TrueHD and DTS-HD, can be transmitted via bitstream mode through the HDMI port. However, as most laptops will feature Optimus, the integrated GPU will likely have direct control over the display ports and may limit the feature set available by the Nvidia Kepler cards.

The 5th generation PureVideo HD video processor (VP5) (also integrated in the GK107 core) offers hardware decoding of HD videos. Common codecs such as MPEG-1/2, MPEG-4 ASP, H.264 and VC1/WMV9 are fully supported up to 4K resolutions while VC1 and MPEG-4 are supported up to 1080p. Two streams can be decoded in parallel for features such as Picture-in-Picture. Another feature is the inclusion of a dedicated video encoding engine similar to Intel QuickSync that can be accessed via the NVENCI API.

Power Consumption

The power consumption of the GeForce GT 740M should be similar to the GT 730M. As a result, the Nvidia GPU is best suited for multimedia notebooks 14-inches in size or greater.