NVIDIA GeForce GTX 950M vs NVIDIA GeForce GTX 965M SLI vs NVIDIA GeForce GTX 980M

NVIDIA GeForce GTX 950M

The NVIDIA GeForce GTX 950M is an (upper) mid-range, DirectX 11-compatible graphics card for laptops unveiled in March 2015. It is based on Nvidia's Maxwell architecture (GM107 chip) and manufactured in 28 nm. The GTX 950M offers 640 shader units clocked at 914 MHz (+ Boost) as well as fast GDDR5 memory (128 bit, 5000 MHz effective, 80 GB/s). Compared to the previous and technically very similar GTX 850M, the GTX 950M is clocked slightly higher. A detailed performance comparison of the GTX 950M with GDDR5 and DDR3 can be found here.

Some GTX 950M may be equipped with cheaper 900 - 1000 MHz DDR3 memory (1800 - 2000 MHz effective, 28.8 - 32 GB/s), which leads to a 10 - 20 percent lower performance despite the slightly higher core clock of 993 MHz.

Architecture

Compared to Kepler, Maxwell has been optimized in several details to increase power efficiency. Smaller Streaming Multiprocessors (SMM) with only 128 ALUs (Kepler: 192) and an optimized scheduler should lead to better utilization of the shaders. Nvidia promises that a Maxwell SMM with 128 ALUs can offer 90 percent of the performance of a Kepler SMX with 192 ALUs. GM107 features 5 SMMs and thus 640 shader cores, 40 TMUs and 16 ROPs (128-bit interface).

Another optimization is the massively enlarged L2 cache (GM107: 2 MB). The increased size can handle some of the memory traffic to allow for a relatively narrow memory interface without significantly reducing the performance.

GM107 supports DirectX 12 with feature level 11_0 only.

Performance

Although the GTX 950M has the same memory bandwidth as the previous GTX 850M, its higher core clock leads to a slightly better performance. Overall, the 950M (GDDR5 version) is about 15 percent slower than the GTX 960M and just slightly behind the old GTX 860M.

Many games of 2014/2015 can be played fluently in FullHD resolution and high detail settings. However, very demanding games such as Assassin's Creed Unity will require lower resolutions and/or details.

Features

GM107 integrates the sixth generation of the PureVideo HD video engine (VP6), offering a better decoding performance for H.264 and MPEG-2 videos. Of course, VP6 supports all features of previous generations (4K support, PIP, video encoding via NVENC API). Unfortunately, HDMI 2.0 is still not supported.

Power Consumption

The power consumption of the GeForce GTX 950M should be similar to (or slightly above) the previous GTX 850M at about 50 watts. Therefore, the GPU is best suited for 15-inch laptops or larger. The 900M series also supports Optimus to automatically switch between an integrated graphics card and the Nvidia GPU.

NVIDIA GeForce GTX 965M SLI

The NVIDIA GeForce GTX 965M SLI is a high-end DirectX 11-compatible graphics solution for laptops, consisting of two GeForce GTX 965M. Each card has a 28 nm GM204 GPU based on the Maxwell architecture, which is the same chip as found on the GTX 980M, GTX 970M as well as several desktop cards. The clocks for the SLI-setup are usually identical to a single GTX 965M (924 MHz GPU, 1250 MHz memory).

With SLI, each card renders a single frame (AFR mode). Therefore, it may suffer from micro stuttering in low fps ranges of 30 fps. This happens because of different timespans between two frames (e.g., irregular delays between sequential frames).

Architecture

GM204 is based on Nvidia's Maxwell architecture, which replaces the previous Kepler generation. Among other changes, Nvidia have restructured the streaming multi processors (SMM) in order to increase workload and efficiency. Now each SMM contains only 128 shader units and 8 TMUs, which is noticeably less than an equivalent Kepler GPU. The GM204 features four GPCs, and each consists of four SMMs. But, in the GeForce GTX 965M, Nvidia have deactivated 8 of 16 SMMs. As a result, only 1024 shader ALUs and 64 TMUs are active. In addition, there are 32 ROPs in two clusters with 16 units each.

The memory interface has a bandwidth of 128-bits (2x 64 bit) for each of the two GPUs. Thanks to an improved compression algorithm, the connection to the GDDR5 memory should be significantly more efficient per MHz. Furthermore, the L1 (96 KB per SMM) and L2 caches (2 MB) have been significantly increased to lower the needed bandwidth. Compared to the mid-range GM107, the newer and larger GM204 has several additional features and changes. Aside from the improved polymorphic engine in the SSMs, it is also the first Nvidia chip to support DirectX 12 Feature Level 12_1.

Performance

With good driver support, SLI almost doubles the performance of a single card. In this case, the GTX 965M SLI beats a single GeForce GTX 980M by about 10 percent. Therefore, the GTX 965M SLI is powerful enough to run even the most demanding games with highest details, AA/AF and/or resolutions exceeding FullHD.

Features

Most of the features are identical to the GeForce GTX 800M series. With the GTX 965M, there can be up to 4 active displays, but this will likely decrease due to Optimus. Displays can be connected with a maximum resolution of 3840 x 2160 pixels via DisplayPort 1.2 or HDMI 2.0 (no HDCP @ 4K). HD audio formats like Dolby True HD and DTS HD can be sent to a compatible receiver as bitstream. As with previous models, 3D Vision is not supported with Optimus.

The video processor VP6 supports the usual formats like H.264 and can also decode and encode H.265 with a resolution of up to 4K via the NVENC API (hybrid H.265 decoder, not fully fixed function). Several parallel streams, such as picture-in-picture in a Blu-Ray movie, are also possible.

Further features of the GTX 900M series, which are also partly supported by older cards, include Battery Boost (longer battery life during gaming), Shadowplay (recording of gaming videos up to 4K60p and 130 Mbit/s) and Gamestream (game streaming on Shield console). More information on these features are available here.

Power Consumption

The power consumption of each GeForce GTX 965M including its MXM board and memory should be around 70 W, leading to a total TDP of about 140 W. Therefore, the SLI setup can only be used in very large and heavy gaming notebooks with powerful cooling systems. Under low load, dynamic clock rates help the GPUs to save energy.

NVIDIA GeForce GTX 980M