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G-Sync vs. Freesync: Which Dynamic Refresh Is Best?

There's a ghost in the machine...

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It feels like whole months since there was a good old fashioned fisticuffs between AMD and Nvidia. They do so love a PR punch up. But this one’s a bit different. Nvidia’s G-Sync technology versus AMD’s FreeSync isn’t the usual trench warfare over fractions of a frame per second. It’s much more interesting than that. It’s all about something called dynamic or adaptive refresh and how that can make games run much more smoothly without necessarily upgrading your video card and even at modest frame rates. G-Sync has been available for a while. But now the first FreeSync panels are out battle can commence…

I’ve covered the basics of adaptive refresh before, so I won’t retread that ground again other than to point out that at the very least you’ll need a new monitor. Instead, I’ll send you over here for a refresher and dive straight into my first impressions.

For context, the systems I played with were running pretty similar panels. The G-Sync was an Asus ROG monitor with a 27-inch 2,560 by 1,440 TN panel, the FreeSync effort matched all those metrics and was made by Acer. Obviously, we’re talking AMD graphics in one rig, Nvidia in the other. For now, Free-Sync is AMD-only and G-Sync is restricted to Nvidia graphics cards. It was ever thus.

Both setups were running in-game and with tech demos supplied by Nvidia and AMD. They’ve cooked up demos to help pinpoint the benefits of dynamic refresh and handily you can run them on each on both platforms, which helps exclude any 3D dodginess.

Anyway, I’ll dispense with the suspense right away by saying that, as things stand, G-Sync is very clearly the better technology by pretty much every metric save for cost. Firstly, it’s just smoother, especially at lower frame rates.

This isn’t a night and day difference. Arguably, the delta is so small that you wouldn’t notice it unless consciously looking out for it. But FreeSync just isn’t as flawlessly smooth at higher frame rates as G-Sync nor does is it as consistent at lower frame rates. It’s worth remembering that as the frame rate drops, there’s a limit to the smoothness that can be achieved with either of these syncing techs. A perfectly synced 20 frames per second is not going to be buttery smooth. But G-Sync still makes a better fist of it, subjectively at least.

Nor is FreeSync as robust. Unfortunately, dynamic refresh is one of those technologies that can have you staring at the screen, scratching your head and wondering whether it’s even working. Is the stuttering you’re seeing because the feature isn’t enabled or because it’s just a bit crap, for instance?

However, when you see screen tearing, you know that it can’t actually be functioning. In some scenarios, that’s exactly what I saw with FreeSync. It didn’t always work in-game when it was switched on. G-Sync always did, as far as I could tell.

Oh god, it’s ghosting…

The final black mark next to FreeSync’s name involves ghosting. I’m actually a little reluctant to call it that since I’m not sure the problem is necessarily the same as the conventional LCD monitor ghosting. But it looks pretty similar and gets the idea across.

Essentially, with FreeSync enabled, a shadowy ‘ghost’ version of moving objects can be seen trailing just behind in their wake. Much depends on speed of movement and the colours of both the objects and the background. But as it happens, it’s particularly apparent with AMD’s FreeSync demo involving a 3D-rendered wind turbine. The ghosting that appears behind the blades with FreeSync enabled is as obvious as it is ugly.

Critically, it’s not there with FreeSync off, regardless of any other settings including refresh rates or V-sync. So it’s not an inherent panel problem. You can also run the same demo on the Asus G-Sync panel with dynamic refresh enabled and clearly see that Nvidia’s solution doesn’t have the same problem.

Moreover, this seemingly response-related problem means the FreeSync panel tends to look that little bit blurrier with FreeSync enabled. Not good. This ghosting issue has been fairly widely reported (there’s a video here showing the issue fairly clearly on a BenQ FreeSync screen) to the extent that I’m fairly confident it’s a general FreeSync issue and not specific to the Acer monitor I saw.

So, what’s going on? Certainly, it’s perilous to take the word of either protagonist on this kind of subject. Agendas are legion.

But based on what I’ve seen and what’s been said, this is my take. Pretty much any modern monitor has image processing electronics. Monitors don’t merely take the signal from your graphics card and chuck it onto the LCD panel untouched.

Instead, they process the signal in a variety of different ways. One of those is aimed at reducing blur and persistence. In other words, improving pixel response. A typical strategy is something known as pixel overdrive which, among other things, involves jolting pixels with increased voltage in order to ramp up response rates.

Anyway, the precise details aren’t all that critical. What matters is that you’re going to notice a negative impact on response and possibly other areas of image quality if the image processing is either not working properly or entirely disabled. Modern monitors look better not just because the panels have themselves improved but also thanks to image processing. Lose the latter and you’ve got a problem.

Nvidia’s G-Sync monitor chipset makes for a more expensive adaptive refresh solution. But for now it also makes for the best…

I suspect this is what’s happening currently with AMD’s Freesync tech. It may well be that technologies like overdrive are only properly supported when the monitor is running within a range of fixed refresh rates supported by its firmware. Turn on dynamic refresh and the image processing is compromised or perhaps bypassed entirely.

Nvidia’s G-Sync tech, by contrast, is essentially a wholesale replacement for the monitor’s image processing chipset and firmware and allows technologies like overdrive to work properly when G-Sync is enabled. This is what Nvidia means when it talks about G-Sync being ‘tuned’ for each panel.

Again, the above is my take on the causes of the ghosting problem. It makes sense, but I’m not absolutely certain it’s precisely what’s happening. If it is, it’s possible in future to imagine monitors with fuller firmware support for FreeSync that allows image processing to function correctly with dynamic refresh enabled.

Either way, I’m not entirely clear on the prospect for fixing the ghosting problem on these early FreeSync panels. As they currently stand, they’re impossible to recommend. At best, I’d characterise FreeSync in it’s existing state as a fun little extra I’d be happy to have for free. But I wouldn’t want to pay a premium or have it dictate my choice of monitor.

G-Sync, on the other hand, is a trickier question. Having seen the two technologies side by side, I’ve a clearer idea of why it’s undoubtedly the better choice right now. Whether I think it’s worth the price premium is another matter.

On balance, I’d probably say not. I’d be happy, merely, with an affordable high refresh panel. Then again, high refresh panels that lack dynamic refresh support are themselves usually still quite pricey and certainly limit your options. The choice between 120Hz and IPS, for instance, isn’t one I want to make. I want to have both.

One day, most monitors will probably be 120Hz-plus and support dynamic refresh and it’ll all work without compromising image quality in other ways. But that’s a few years away yet, at best.

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Jeremy Laird


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