NVIDIA GeForce GTX 980 Ti Review: A Cheaper Titan X Arrives

DX12 Update and New G-Sync, VR Features

In addition to launching the GeForce GTX 980 Ti today, NVIDIA is making a handful of other announcements related to DirectX 12, G-SYNC, and VR.

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NVIDIA first wanted to point out that the GeForce GTX 980 Ti, and other Maxwell based cards, support DX12 feature level 12_1, which includes technologies dubbed Conservative Raster and Raster Order Views. An additional feature, Volume Tiled Resources, is also supported. With tiled resources, only the portions of the textures that are required for rendering are stored in the GPU’s memory. Tiled Resources works by breaking textures down into tiles, and the application determines which tiles might be needed and loads them into video memory. This feature can allow game developers to produce better looking graphics with less memory. Tiles Resources were limited to 2D objects previous, but with Volume Tiled Resources, the capability is extended to volume (3D) textures.

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In the interest of saving time (and clarity), I’m going to quote NVIDIA directly to explain Conservative Raster. “Conservative Raster provides a more accurate method for determining whether or not a pixel is covered, at the cost of being more expensive in terms of performance. In traditional rasterization, a triangle is considered covered if a pixel covers a specific sample point within that pixel, for example, the center of the pixel in the example below. With conservative rasterization rules on the other hand, a pixel is considered covered if any part of the pixel is covered by any part of the triangle.”

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Another new feature NVIDIA is disclosing today that is part of Gameworks VR is called Multi-Res Shading. Due to the configuration of the optics in today’s VR systems, and the way the final rendered image has to be warped into the correct shape to allow the human eye to perceive the images on the VR screens properly, there are lots of unseen pixels rendered.

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The way things are today, there ends up being a large portion of the rendered images around the edges that’s never actually seen by the user. And GPU resources are wasted rendering those pixels.

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With Multi-Res Rendering, NVIDIA is subdividing the image into viewports and rendering some of them (the outer edges—the center remains untouched) at lower resolutions, which translate to the proper resolution for the final warped image. The end result in a 1.3x to 2x improvement in pixel shader performance. Technically, the final rendered image isn’t pixel-perfect, but the approximation was excellent in some demos we tried.

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There are also a couple of updates coming to G-SYNC. NVIDIA will now be supporting windowed mode G-SYNC and a handful of new G-SYNC monitors are coming as well. To pull off the windowed mode G-SYNC, NVIDIA is working a little magic in their drivers to bypass some limitation of the built-in Windows Desktop Windows Manager. Windowed G-SYNC will be limited to the app in focus, and there are some legacy apps that could have issues, but this is a feature some gamers will dig.

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Asus and Acer also have an array of new G-SYNC ready monitors coming down the pipeline, including some new IPS and VN panels, at resolutions up to 4K.

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