NVIDIA GeForce GTX 760M vs NVIDIA GeForce GTX 765M SLI

NVIDIA GeForce GTX 760M

The NVIDIA GeForce GTX 760M is a upper mid-range DirectX 11-compatible graphics card for laptops. In contrast to the GTX 660M, the 760M now uses the GK106 chip and offers twice the amount of shaders at a slightly reduced core speed. However, the memory bus is still only 128 Bit wide.

As a novelty, the GeForce 700M series implements GPU Boost 2.0 to automatically overclock the core clock rate. Depending on the cooling headroom of the laptop and the application / game, up to 15 % performance gains are possible.

Architecture
The Kepler architecture is the successor to the Fermi architecture that first appeared in laptops with the GeForce 400M series. The GK106 Kepler core offers five shader blocks, called SMX, that are clocked at the same speed as the central core. In the GTX 760M, four blocks are active for a total of 768 CUDA cores. Although the Kepler architecture can utilize more shader cores than a Fermi chip, its shaders can 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 of similar speed to 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 graphics performance of the GeForce GTX 760M is clearly above the GTX 660M thanks to the higher amount of shaders. Depending on the GPU Boost 2.0 up to 30 % better performance can be achieved (according to Nvidia).

In our tests with a quad-core of the Haswell generation, the GTX 760M performs on par with a GTX 670M or Radeon HD 8870M. In demanding games like Crysis 3, BioShock Infinite or Hitman: Absolution the GTX760M is able to achieve good framerates in high details and 1366x768 pixels. Less demanding games like Dead Space 3, Modern Warfare 3 or Deus Ex Human Revolution were even playable in Full HD and maximum details.

Features
The feature set of the GTX760M is identical to the GTX670MX as both are based on the same GK106 core. Therefore the GPU supports 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 GK104 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. Finally, the dedicated video encoding engine called NVENC API similar to Intel QuickSync is integrated in the chip.

The power consumption of the GeForce GTX 760M should be similar to the GTX 660M (50W) and is therefore best suited for large notebooks (15-inches or greater) and desktop replacements.

NVIDIA GeForce GTX 765M SLI

The NVIDIA GeForce GTX 765M SLI is a high-end DirectX 11-compatible graphics solution for laptops, consisting of two GeForce GTX 765M. Each card has a 28nm GK106 core based on the Kepler architecture. The clocks for the SLI-setup are identical to a single GTX 765M. With SLI, each card usually renders a single frame (AFR mode). Therefore, it may suffer from micro stuttering in low fps ranges below 30fps. This happens because of irregular delays between two sequential frames.

Architecture

The Kepler architecture is the successor to the Fermi architecture that first appeared in laptops with the GeForce 400M series. The GK106 Kepler core offers five shader blocks, called SMX, that are clocked at the same speed as the central core. In the GTX 765M, only four blocks are activated (= 768 CUDA-Cores for each 765M). Although the Kepler architecture can utilize more shader cores than a Fermi chip, its shaders can 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 of similar speed to 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 graphics performance of the GeForce GTX 765M SLI is about 70 - 80 percent above a single GTX 765M, making it as fast as a single GeForce GTX 680M. Therefore, most games as of 2013 are playable at the highest detail setting and in FullHD resolution. In many cases it is even possible to activate additional anti-aliasing.

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) is also integrated in the GK106 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.

Power consumption

The power consumption of the GeForce GTX 765M SLI should double that of a single 765M at about 120 - 130 W including the boards and memory. Therefore, the dual cards are well-suited for large desktop replacements.