The New Age of Multi-GPU

With Microsoft DirectX 12 introducing a standardized mixed multi-GPU mode in which a DirectX 12 (and above) 3D app can take advantage of any number and types of GPUs as long as they support the API features needed by the app, multi-GPU has changed forever. Instead of steering its GPU lineup toward that future, NVIDIA has spent some R&D on its proprietary SLI technology. With increasing resolutions and refresh rates straining the bandwidth of display connectors and inter-GPU communication in multi-GPU modes, NVIDIA decided that SLI needs added bandwidth. One way it saw to doing so was to task both SLI contact points on the graphics card in a 2-way configuration. Enter the SLI HB (high-bandwidth) bridge, a rigid SLI bridge that comes in 1U, 2U, and 3U slot spacings for a link between two GeForce "Pascal" graphics cards along both their SLI "fingers" (contact points). This allows a SLI duo to more reliably render at such resolutions as 4K @ 60 Hz or 120 Hz, and 5K, or HDR-enabled resolutions. SLI could still work with a classic 2-way bridge at any resolution, but that could adversely affect performance upscaling, and the output won't be as smooth as with an SLI HB bridge. This also appears to be why NVIDIA discontinued official support for 3-way and 4-way SLI.



The GTX 1080 still supports 3-way and 4-way SLI over the classic bridges that come with motherboards, but you would have to obtain a special software key from NVIDIA and would rely on your game/benchmark developers to optimize their apps for 3-way/4-way SLI. NVIDIA's regular driver updates will likely only optimize for 2-way SLI. Enthusiasts wanting to use 3-way or 4-way SLI would download an app from an upcoming "Enthusiast Key" website, run the app, and generate a software key signature for their hardware to unlock 3-way and 4-way SLI in NVIDIA's Control Panel. NVIDIA "Pascal" GPUs do support Microsoft DirectX 12's multi-display adapter (MDA) mode, but NVIDIA will not provide game-specific optimizations through driver updates for MDA. That would become the game developer's responsibility. The same applies to "explicit" LDA (linked display adapter).

New Display Connectors

The "Pascal" architecture features DisplayPort 1.4 even though it's only certified for up to DisplayPort 1.2. You can enjoy all the features of DisplayPort 1.3 and 1.4 just fine, such as HDR metadata transport. The GPU also supports HDMI 2.0b, the latest HDMI standard with support for HDR video. In the entire course of its presentation, NVIDIA did not mention whether "Pascal" supports VESA AdaptiveSync, which AMD is co-branding as FreeSync. All you need for it to work is a GPU that supports HDMI 2.0a or DisplayPort 1.2a (which are both satisfied by NVIDIA supporting HDMI 2.0b and DisplayPort 1.4). All that's needed is support on the driver's side. The GeForce GTX 1080 features an HDMI 2.0b, a dual-link DVI-D, and three DisplayPort 1.4 connectors. The DVI connector lacks analog wiring, and, thus, the GTX 1080 lacks support for D-Sub monitors through dongles.

Fast Sync

With each new architecture over the past three generations, NVIDIA toyed with display sync. With "Kepler," it introduced Adaptive V-Sync, by the time "Maxwell" came along, you had G-SYNC, and with "Pascal," the company is introducing a new feature called Fast Sync. NVIDIA states Fast Sync to be a low-latency alternative to V-Sync that eliminates frame-tearing (normally caused because the GPU's output frame-rate is above the display's refresh-rate) while letting the GPU render unrestrained from V-Sync, which reduces input latency. This works by decoupling the display pipelines and render output, which makes temporarily storing excessive frames that have been rendered in the frame buffer possible. The result is an experience with low input-lag (from V-Sync "off") and no frame-tearing (from V-Sync "on"). You will be able to enable Fast Sync for a 3D app by editing its profile in NVIDIA Control Panel; simply force Vertical Sync mode to "Fast."

Simultaneous Multi-Projection

With "Pascal," NVIDIA introduced a new hardware-accelerated feature that corrects display output to an arrangement of physical displays, by simultaneously rendering the same 3D scene through multiple different perspectives at low rendering cost. This gives you more accurate surround-view output.

Ansel

Ansel is less a gamer-specific and more "in-game photography" specific feature. There is, apparently, a thriving industry for pictures based on beautiful, scenic in-game screenshots. Ansel lets you freeze a supported game and play with its lighting effects for that perfect screenshot.

HDR takes Centerstage

High Dynamic Range, or HDR, isn't a new concept in photography. It isn't even new to PC gaming, as some of the oldest games with HDR (using simple bloom effects) date back to the Valve Source engine (early 2000s). Those apps, however, used the limited 24-bit (8-bit per color, 16.7 million colors in all) color palette to emulate HDR. Modern bandwidth-rich GPUs such as the GTX 1080 have native support for large color palettes, such as 10-bit (1.07 billion colors) and 12-bit (68.7 billion colors), to accelerate HDR content without software emulation. This includes support for 10-bit and 12-bit HVEC video decoding at resolutions of up to 4K @ 60 Hz, or video encoding at 10-bit for the same resolution.