What is G-Sync, and why do you need it?
Tearing in games is caused by a disagreement between when your graphics card is sending a signal to the monitor, and how fast the monitor can actually display it. If you have a 60Hz panel, and your card is rendering at 60 frames per second, then there’s no issue. Sway above or below that sweet spot, though, and things start to get weird. Tearing specifically happens when the display isn’t done displaying one frame when another is sent to it from the graphics card.
V-Sync solves the issue by limiting the framerate of your game to the maximum refresh rate of your monitor. It’s a simple solution, and assuming your computer keeps a steady 60 frames per second, the only real downsides are that you’re technically limiting your performance if your framerate could be higher, which can result in input lag.
The input lag issue is complex, but it all boils down to how quickly frames are produced. Let’s say a game is producing 90 frames per second on average. Roughly speaking, that means a frame is produced once every 11 milliseconds. If V-Sync is enabled, and framerate is capped to 60 FPS, then a frame is produced roughly every 16.7 milliseconds. The time a frame takes to render is the most basic form of input lag, and because V-Sync reduces the speed with which frames appear, it increases lag.
If you turn off V-Sync, however, the cadence of frames being produced at 90 FPS won’t vibe well with the typical monitor’s 60Hz refresh rate. The result will be horizontal tearing across the screen – especially noticeable during rapid movement in-game. Neither solution is ideal.
G-Sync tries to provide the best of both worlds.
Input lag under V-Sync becomes even worse if your framerate is below 60 FPS. Let’s say a game is averaging 50 FPS, for example. That’s not enough to match a 60Hz refresh rate, so to continue providing a tear-free experience, V-Sync must drop down to an even power of 60 – the closest being 30 FPS. Your video card is now putting out one frame for every other display refresh, which means one frame every 33.3 milliseconds, on average.
G-Sync tries to provide the best of both worlds. In a desktop setting, the graphics card talks to a proprietary module in a compatible monitor over DisplayPort, and refreshing the display only when the graphics card has rendered another frame. In a laptop, the process is much simpler, as the GPU and monitor are already closely integrated. Because the display refreshes only when a frame is produced, there’s no tearing – but there’s also no additional input lag. In theory, at least.
We tested G-Sync on the well-equipped Asus G751Y-DB72, which is almost identical to the Asus G751 we tested in October of 2014. It boasts an Intel Core i7-4720HQ processor, 24GB of RAM, and an Nvidia GeForce GTX 980M, the company’s best mobile graphics chip.
If you don’t mind hauling it around, there’s not much to complain about, especially when it comes to performance. The massive gaming laptop has the chops to tackle even the most demanding game in our review suite, and turning up the heat will push the performance down to a point tearing will be an issue.
The processor in the model we used to review G-Sync is slightly upgraded from the Intel Core i7-4710HQ to the i7-4720HQ, and the refresh rate on the display is now 75Hz instead of 60Hz, but most users won’t see any difference between the chips. In fact, the display itself is likely the same. Users of the old model have reported overclocking the older display to 80Hz or higher without issue.
Other than the processor, the only difference is the G-Sync sticker next to the keyboard. Compatible laptops with an Nvidia GTX 965M, 970M, or 980M can have G-Sync enabled through a driver update, but how effective it is will depend on your screen’s refresh rate.
Nvidia Tech Demo
If there’s an easy way to see the difference between the three different modes, it’s Nvidia’s Pendulum tech demo. The simple swinging animation of a detailed rendering of the slow arc of a golden pendulum lets the viewer switch between V-Sync, G-Sync, and no refresh management software at the click of a button.
Without any refresh management, the tearing on the golden face of the pendulum is acute, and can be seen especially at the bottom of the swing, when it’s moving the fastest.
The effects of G-Sync are even clearer when you step away from the pendulum and render a vertical test bar. It moves back and forth across a black screen, and you can see the pronounced effects of tearing, the stutter of V-Sync, and G-Sync’s smoothing properties very clearly.
Real world tests
More important than how well G-Sync performs in a tech demo is how well it manages tearing in actual video games. In order to enhance the effects of G-Sync, and because we don’t want to make it too easy, the settings on each title are set as high as possible. The Asus G751 proves a formidable opponent, and both Diablo 3 and Shadow of Mordor are able to stay at or above the display’s natural 75Hz refresh rate consistently. GTA V and Battlefield 4 are both taxing enough to drop the framerate into the 40-60fps range, where tearing and other artifacts are most noticeable.
You might not think of Blizzard’s top-down RPG when it comes to graphical demands, but the flurry of animations, fast input requirements, and framerate fluctuations actually make it extremely susceptible to tearing and other artifacts. Sure enough, with no V-Sync or G-Sync, the rapid spinning of the barbarian’s sword tears and skips badly, especially with graphical settings turned all the way up.
This is a game, however, where G-Sync doesn’t make much of a difference over V-Sync. Because Diablo 3 isn’t particularly demanding, the Asus is able to keep the framerate glued to the upper limit, even with the graphical settings turned up. The only real difference is that the upper limit with V-Sync is 60, while the upper limit with G-Sync on is 75.
Graphical artifacts aren’t particularly bad in Rockstar’s newest title, but tearing can be noticeable when spinning quickly, especially with the amount of background animation happening on screen. With the graphics settings turned up to a mixture of very high and ultra, this tearing becomes more pronounced, and turning on V-Sync generates uncomfortable stuttering, although input lag stays fairly consistent.
G-Sync really smooths out gameplay. Even as the framerate drops into the 30s, it doesn’t stutter or tear. Input lag stays as sharp as possible, although GTA doesn’t require the snappiest response times to begin with. This game proved a good example of G-Sync’s benefits.
Shadow of Mordor
As one of the games that stays above the 75 FPS threshold on the G751, the effects of tearing weren’t as noticeable in general gameplay. Without refresh management on, tearing is focused in areas with complex interaction, like pant legs with a shadow, as well as on objects in the distance. It can also be noticeable when weather effects kick in – the rain in the benchmark may be at least partially responsible for the rippling you see at the bottom of the screen.
Swinging your sword won’t make the whole screen rip, but those mountains and trees in the background might be chopped in half. V-Sync smooths the problem out significantly. Because of the high framerates experienced, there isn’t a noticeable difference between V-Sync and G-Sync.
EA’s Battlefield 4 provides a great example of the benefits of G-Sync, at least compared to not having any sort of refresh management turned on. The busy map design and twitchy combat mean that all of the issues that G-Sync proposes to resolve are present and accounted for. The ultra graphics preset stresses our system just enough to put the framerate between 50 and 75, a sweet spot for tearing and stuttering on the Asus’ 75Hz display.
With no refresh management at all, fast turns of any sort cause tearing across the whole screen, but the response is sharp. Firing or switching weapons causes artifacts as well, though they aren’t as noticeable. Turn V-Sync on, and the framerate can no longer keep up with the refresh rate of the screen. Stuttering isn’t terribly noticeable, aiming and jumping feels a bit slower to respond.
With G-Sync on, the tearing disappears, but input lag is not increased. You can spin around and aim down the sights repeatedly without any delay or stuttering, even as the framerate rises and falls. All the issues G-Sync aims to tackle are fixed with no negative effect.
Ultimately, the need for G-Sync is going to have a lot to do with how much you’re willing to spend on a system, and how badly tearing bothers you. The first qualification is a simple one, as you’ll need at least a GeForce 650 Ti Boost, plus displays with a G-Sync module tend to run about $150-200 more than their non-G-Sync version.
If you’re already planning on spending $1,000 or more on a gaming rig, you’re likely to buy that card or better, and you’ll be spending a bit on the monitor anyway, so it really comes down to preference. G-Sync is not for budget rigs, but the premium isn’t intolerable.
The advantage over V-Sync is clear. G-Sync operates cleanly, and doesn’t drop framerates in any game we tested.
Furthermore, if you’re on a laptop that already has one of these high end mobile cards in it, G-Sync is only a driver update away – if your laptop is supported. Even on a display with a 60Hz refresh rate, you’ll find the smoothing and tearing reduction that G-Sync provides are preferable to V-Sync’s input lag and stuttering.
The advantages over V-Sync are clear. G-Sync operates cleanly, and doesn’t drop framerates in any of these games. The two technologies aren’t mutually exclusive, either. When your framerate is over the maximum refresh rate of the monitor, it’s akin to using V-Sync, and if an explosion or newly rendered detail causes the framerate to drop, G-Sync takes over once again.
There’s little reason not to make use of G-Sync if your system already supports it. It smooths out artifacts and odd graphical issues at all performance levels while using little, if any, system resources. Similarly, if you’re building a gaming system and plan on installing an Nvidia card before picking up a nice monitor, it’s worth grabbing one that has G-Sync built in.
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