Nvidia GeForce GTX 970 and 980 reference review

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New technologies

Nvidia has added a handful of new technologies to the product, I wanted to quickly introduce some of them, though in advance these are very limited as I had very little time for our reference article this round.

DSR - Dynamic Super Resolution

Taking the 4K experience and allowing you to visualize that on a 1080P monitor is what DSR is about. It renders the game at a higher resolution and shows it in a lower one, this brings more quality to that lower resolution.

Ac4-1-dsr4xmsaa_scaled

AC4 DSR 4xMSAA scaled

In general DSR works like downsampling, but it has simple user on/off control. Textures will now be sampled at higher resolutions that equates to more pixels being sampled. Then a filter is applied (13 TAP Gaussian). This high quality filter reduces or eliminates AA artifact experiences with normal down-sampling, which relies on a simpler box filter. The new feature can be activated through GeForce Experience and drivers.

Bf4-1-dsr4xmsaaultra_scaled

BF4 DSR 4x MSAA Ultra scaled

The feature will launch with Maxwell, but it is likely that you will see this feature on older generation GPUs as well. It will have a performance hit, meaning if you downsample from UHD you will see the same performance as rendering at that resolution. To recap, Dynamic Super Resolution works by rendering the game at a higher resolution, then scaling the image down to the native resolution of the user’s display on output. For example, a gamer with a 1080p display could use Dynamic Super Resolution to have the GPU render an image that looks nearly like 4K resolution on their existing display.  Dynamic Super Resolution uses a 13-tap Gaussian filter during the conversion to display resolution. This high-quality filter reduces or eliminates the aliasing artifacts experienced with downsampling, which relies on a simpler box filter. If you like to try it out, simply open the control panel and navigate to Manage 3D Settings -> DSR Factors to select your screen resolution (settings ranging from 1.2x-4.0x native resolution in the current implementation) and use the DSR Smoothness setting to adjust the Gaussian filter, then launch your game. You should be able to find the new DSR resolution inside the graphics menu settings of the newly launched game.

Multi Frame Sampled AA

Nvidia is introducing a really nice new AA mode called MFAA – MFAA is short for Multi Frame Sampled AA. It gives the same quality as 4x MSAA but has only the performance costs of 2x MSAA. It is based on a Temporal Synthesis Filter with coverage samples per frame and per pixel. If the framerate is low it will start flickering, the filter starts to decide then whether or not to apply. Utilizing a new hardware feature found in the GeForce GTX 980/970 (programmable AA sample positions), MFAA alternates between multiple AA sample patterns to produce the best image quality while still offering a performance advantage compared to traditional MSAA. In our 4xMSAA example, MFAA alternates between two different 2xAA sample patterns that are blended together with a temporal synthesis filter to produce an image that looks similar to 4xMSAA to your eye. The performance hit is low for the filter, less than 2% MFAA is still under development and should be released fairly soon after which we'll check it out. But it is a promising new AA alright.

VXGI (Voxel Global illumination)

VXGI is the next step in lighting for gaming and, in simple wording, a new real-time global illumination engine technology. Global illumination is often used in the movie industry to produce CG scenes. VXGI is based on using a 3D structure (Voxels) to capture coverage and lighting information at every point in a scene. This data structure can then be traced during the final stage of rendering to precisely determine the effect of light bouncing around in the scene. VXGI provides improved performance for global illumination. This software algorithm will only work with Maxwell GPUs.

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No this is not a photo - it is a scene from an Nvidia tech demo with VXGI in full effect

The performance hit is dynamic as it is scalable due to the number of steps and cones your use to render. It is a real-time practical solution for gaming at 40 to 60 FPS with incredible lighting detail. It will be available to developers through Nvidia Gameworks.

HDMI 2.0

Nice to see is that HDMI is now supported at revision 2.0. HDMI 2.0 is the successor to the HDMI 1.4a/b standard that we pretty much all use in this day and era. The primary reason to bring 2.0 support to Maxwell is that 4K Ultra HD televisions require more bandwidth to operate at their full potential. 4K Ultra HD is four times the resolution of 1080p and therefore UHD needs more throughput to manage that extra data going back and forth. So didn't my UHD TV work at HDMI 1.4 you might wonder? Yes, but only at 24 or 30 frames per second. That works OK for movies, but is of no use for gaming and TV broadcasts, which require 50 or 60 fps. HDMI 1.4 also limits 4K Ultra HD content to 8-bit color, but it is capable of 10 or 12-bit color. HDMI 2.0 can handle up to 18 gigabits per second. That’s plenty enough to allow for 12-bit color and video up to 60 frames per second. There are advantages audio wise as well; HDMI 2.0 can carry 32 channels of uncompressed audio. FYI - the latest Dolby Atmos surround format is capable of 64 channels of surround in the theaters. Scaling it back to 32 channels (or less) for a home-brewed version of Dolby Atmos is now within grasp. HDMI 2.0 changes nothing about the size, shape or wiring of HDMI cables. In fact, your existing cables will work fine. Also HDMI 2.0 is backward compatible with older HDMI versions, you’ll be able to connect your old Blu-ray player and/or A/V receiver to a newer HDMI 2.0-equipped 4K Ultra HD. With HDMI 2.0, the GPU can now drive full-resolution “444” RGB pixels at 4K resolution at 60Hz.

NVENC encoder updates

GM2xx Maxwell also ships with an enhanced NVENC encoder that adds support for H.265 (also known has HEVC) encoding. H.265 compression offers significant bandwidth savings versus H.264 at the same quality level, which will help enable the next generation of streamed gaming experiences within the home or powered by the cloud. In addition, Maxwell’s video encoder improves H.264 video encode throughput by 2.5x over Kepler, enabling it to encode 4K video at 60 fps.

DirectX 12

Microsoft’s upcoming DirectX 12 API has been designed to have CPU efficiency significantly greater than earlier DirectX versions. The DX12 release of DirectX will introduce a number of new features for graphics rendering. Microsoft has disclosed some of these features, at GDC and during NVIDIA’s Editor’s conference. Conservative Raster, discussed earlier in the GI section of this paper, is one such DX graphics feature. Another is Raster Ordered Views (ROVs,) which gives developers control over the ordering pixel shader operations. GM2xx supports both Conservative Raster and ROVs. The new graphics features included in DX12 will be accessible from either DX11 or DX12 so developers will be free to use the new features with either the DX11 or DX12 APIs.

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