NVIDIA GeForce GTX 780M vs NVIDIA GeForce 830M

The NVIDIA GeForce GTX 780M is a high-end DirectX 11-compatible graphics card for laptops. It is based on the same chip as the GeForce GTX 680MX but offers a higher core clock at a lower TDP. It is based on the 28nm GK104 Kepler architecture similar to the GTX 680M, but features more CUDA cores (1536 vs. 1344), a higher clock rate and GPU Boost 2.0. As of summer 2013, it is the fastest laptop graphics card on the market.

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 GK104 Kepler core offers eight shader blocks, called SMX, that are clocked at the same speed as the central core. In the GTX 780M, all eight blocks are active for a total of 1536 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
In our gaming tests the GeForce GTX 780M was able to gain a 30 percent lead to the older Nvidia Geforce GTX 680M thanks to the additional shader cores and higher clock rates. That makes the GTX 780M the fastest single mobile graphics card in summer 2013 and 10 - 15 percent faster than the AMD Radeon HD 8970M. The GPU has enough power to run demanding games of 2012 fluently with Full HD resolution and maxed out graphical settings. Battlefield 3, Skyrim, and Crysis 2, for example, are playable at the highest detail settings (see benchmarks below).

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 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. 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 GTX 780M should be similar or slightly higher than the GTX 680M (100 Watt TDP). According to rumors it should stay below the GTX 680MX in the iMac but still it is best suited for 17-inch desktop replacement laptops.