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What is Nvidia Fast Sync and What Does it Offer Gamers?

Posted by Jamie on October 15, 2018

When Nvidia released the Pascal and Maxwell GeForce GTX graphics cards, a new feature came with them, Fast Sync. Designed to provide an alternative to V-Sync that delivered lower latency and no tearing, it could be the answer to gamer’s prayers. So what is Nvidia Fast Sync and what does it offer gamers?

Graphics card manufacturers are always pushing the boundaries. Both to continually offer us something new and reasons to part with our money and to keep up with the competition. For too long Nvidia had the upper hand and innovation seemed to slow. Now with AMD fully back in the game, technologies are being developed and the graphics card arms race is back on.

While the industry moves apace and the RTX cards are on their way, Pascal and Maxwell will still be affordable options for those of us who cannot afford to drop $500 on a graphics card.

What is screen tearing?

As Nvidia Fast Sync is designed to reduce screen tearing and latency, we need to know what the former is so we can fully understand the advantages of Fast Sync. Screen tearing is where you will see a disconnect between two parts of the screen. If you imagine you’re looking at a corner of a wall in a game and it look as though the top half is half an inch to the left or right of the bottom, this is tearing.

Screen tearing occurs when there is a mismatch between the speed at which the graphics card sends the image and the speed at which the monitor can display it. If you’re using a 60Hz monitor, that means a refresh every 16ms. If the graphics card sends a frame too early, screen tearing occurs as the monitor isn’t ready for it. You will see part of the old frame and part of the new one and they won’t match, hence the tear.

V-Sync was designed to synchronize the GPU and monitor refresh rate but came at a cost. Latency. Latency came when the graphics engine would be choked as there was still a frame in the back buffer awaiting delivery to the monitor.

What is Nvidia Fast Sync?

If you ever tried using V-Sync, you will have noticed a reduction in screen tearing but an increase in input lag. This will be especially true if you play fast-paced games. Many pro gamers preferred to deal with screen tearing than the latency of V-Sync so it went largely unused. Nvidia Fast Sync is designed to fix that.

By introducing the last rendered buffer, Nvidia hopes to eliminate both screen tearing and latency. Nvidia already uses a back buffer and front buffer to render frames.

The graphics engine feeds the back buffer with a complete frame which is fed into the new last rendered buffer. The engine then immediately moves on to the next frame. The last rendered buffer sends the frame to the front buffer which continually scans for new frames and sends them to the monitor.

Adding an extra step to the process allows a tiny amount of time for the GPU to deliver a full frame to the monitor without latency. This is because the back buffer is always available to receive another frame from the engine. This continual shuffling of frames is coordinated to deliver frames as fast as the hardware is capable of. The result is the delivery of complete frames at the maximum speed the hardware is capable of delivering and displaying.

The benefit to gamers is clear. You get less screen tearing with none of the latency you would see if you were using V-Sync. When you’re playing fast twitch games, this can make a real difference.

How to enable Nvidia Fast Sync

If you want to use Nvidia Fast Sync you will need to use it through the Nvidia Control Panel.

  1. Right click an empty space on your desktop and select Nvidia Control Panel.
  2. Select Manage 3D Settings.
  3. Select Vertical Sync in the center pane.
  4. Select the dropdown to the right and select Fast.
  5. Select Apply.

If you decide to change the setting from use application setting to fast, you will need to make sure V-Sync is manually disabled in all your games. Most have it set this way but some games like to use V-Sync without telling you. If you have issues with graphics after making this change, go into the graphics settings and make sure V-Sync is off.

I use Nvidia Fast Sync and it works well. I see little or no screen tearing and no perceptible latency. I only play a couple of fast twitch games but even with those the rendering seems smooth and silky even on my old GTX 970.

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