AMD Freesync Review
Published: 19th March 2015 | Source: AMD | Price: Range @ OCUK |
So How Does It Work?
We know that the OC3D readers are a knowledgeable bunch but we all had to start somewhere so let's quickly run over how vertical synchronisation (VSync) works courtesy of the orange-loving nerdy spod of the OC3D team.
Images from games are just like a film, in that they are a series of still images that change just enough, and are shown quickly enough, to give the illusion of movement. On a 60Hz monitor the screen updates 60 times a second. Your graphics card always renders each frame as quickly as possible. So sometimes your graphics card renders a frame that your screen hasn't got time to display, for example your game is doing 100FPS, and so some of them get discarded. Alternatively your screen can sometimes be ready to refresh but your graphics card hasn't finished and so some frames are duplicated.
You can almost imagine your monitor as a demanding boss, and your graphics card as a hard worker. "Hey I'm ready for the next frame", "Sorry boss, haven't finished it, show the one we've already got again". That's bad for gameplay fidelity. Anyone who's endured playing a racing game or trying to snipe when the frame rate slows to a crawl will know how difficult it is to hit accurately. Of course this boss/worker arrangement works both ways. Not every game is as lethargic as Metro, some easily hit triple digits, in which case it's more like "Hey boss, I've got a dozen frames ready for you", "I'm still showing the last one", "Okay I'll just bin them then". Usually followed by your GPU muttering under its breath. Turning VSync off means that the
Freesync solves this problem of frames either piling up or not being ready by only refreshing the monitor when there is a new frame ready to display. This not only benefits the responsiveness of your inputs, but also ensures that you'll never endure screen tearing again.
There is a small elephant in the room, namely nVidia's GSync, which does exactly the same things. In fact if anything we take issue with AMD's use of the word Proprietary. Yes nVidia require a monitor with GSync support, but AMD require a monitor with Freesync support. Just because there isn't a piece of hardware doing the decoding doesn't mean it works on anything.
The big show-stopping claim is how little performance hit you endure by enabling Freesync. If it manages to perform without an overhead is something we can't wait to discover, and will do so in a couple of pages time.