NVIDIA GeForce GT 650M vs NVIDIA GeForce GT 750M vs NVIDIA GeForce GT 650M SLI

NVIDIA GeForce GT 650M

The NVIDIA GeForce GT 650M is a mid-range, DirectX 11.1 compatible graphics card that was announced in the first quarter of 2012 for laptops. It is a Kepler-based GPU built on the GK107 architecture and is manufactured in 28nm at TSMC. The graphics card uses a 128-Bit wide memory interface with either the more common but slower DDR3 for VRAM or the more expensive and faster GDDR5. Due to a higher core clock of up to 850 MHz the GT 650M is noticably faster than the 640M.

Architecture

The Kepler architecture is the successor to the Fermi architecture that first appeared in laptops with the GeForce 400M series. 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 central core. Although more shader cores are available in the Kepler architecture as compared to the Fermi design, the Kepler shaders are still expected to be up to twice as power efficient. However, due to the missing hot clock of the shader domain, two shaders of a Kepler chip are about as fast as one shader of a Fermi chip (as the latter is clocked twice as fast). PCIe 3.0 is now supported by the mobile Kepler series and an optional Turbo mode can automatically overclock the Nvidia card by a theoretical 15 percent if the laptop cooling system allows it. The implementation of this boost mode is done in the BIOS, but it is ultimately dependent upon the manufacturer of the laptop.

Performance

The gaming performance of the GeForce GT 650M equipped with DDR3 graphics memory is somewhere in the former 2011 high-end category between the GeForce GTX 460M and GTX 560M. The performance is exceptionally good in shader-heavy DirectX 11 games and benchmarks. However, the 128-Bit memory interface can be a bottleneck if DDR3 graphics memory is employed. Despite the slower core clock of only 735 MHz, the GDDR5-version of the card should be similar fast. Demanding games of 2011 like Battlefield 3 will be playable in 1366x768 and medium or high settings. Less demanding games, such as Modern Warfare 3, are easily playable with maxed out settings and 1080p resolution.

Features

The improved feature set now 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) is also integrated in the GK107 core and 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 novelty is the inclusion of a dedicated video encoding engine similar to Intel QuickSync that can be accessed by the NVENC API.

The power consumption of the GeForce GT 650M should be best suited for medium-sized notebooks 15-inches or greater.

NVIDIA GeForce GT 750M

The NVIDIA GeForce GT 750M 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. The GK107 chip (384 shaders) is clocked at up to 967 MHz plus boost and has a 128 bit memory interface (mostly DDR3, but GDDR5 also possible).

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

Depending on clock speed, the GT 750M with DDR3 memory is about 10 - 15 percent faster than the GT 650M. The very rare GDDR5 version even beats the GTX 660M. Most current games (as of 2013) can be played fluently in high settings. In older titles, there are also reserves for additional quality features like AA and AF. Detailed benchmarks can be found further down on this page.

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. 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 750M should be somewhere between the GT 650M and GTX 660M (about 35 - 40 watts). As a result, the Nvidia GPU is best suited for notebooks 15 inches in size or greater.

NVIDIA GeForce GT 650M SLI

The NVIDIA GeForce GT 650M SLI is a high-end DirectX 11-compatible graphics solution for laptops, consisting of two GeForce GT 650M. 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). The 650M SLI is currently used only in the Lenovo Y500 with fast GDDR5 graphics memory and clock rates of 790 to 835 MHz (GeForce Boost).

Architecture

The Kepler architecture is the successor to the Fermi architecture that first appeared in laptops with the GeForce 400M series. 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 central core. Although more shader cores are available in the Kepler architecture as compared to the Fermi design, the Kepler shaders are still expected to be up to twice as power efficient. However, due to the missing hot clock of the shader domain, two shaders of a Kepler chip are about as fast as one shader of a Fermi chip (as the latter is clocked twice as fast). PCIe 3.0 is now supported by the mobile Kepler series and an optional Turbo mode can automatically overclock the Nvidia card by a theoretical 15 percent if the laptop cooling system allows it. The implementation of this boost mode is done in the BIOS, but it is ultimately dependent upon the manufacturer of the laptop.

Performance

The gaming performance of the SLI combination ranges between a GeForce GTX 670MX (maximum, e.g. in 3DMark 11 benchmarks) down to a single GeForce GT 650M (if SLI is not supported by the game). On average the 650M SLI could therefore be placed a bit above a Geforce GTX 660M in the high-end class. Modern games of 2012 should therefore be playable with high detail settings.

Features

The improved feature set now 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) is also integrated in the GK107 core and 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 novelty is the inclusion of a dedicated video encoding engine similar to Intel QuickSync that can be accessed by the NVENC API.

The power consumption of the GeForce GT 650M SLI should double compared to a single GTX 650M. Therefore, only large laptops can handle the heat dissipation.