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A few days ago, one of our readers raised the idea that G-Sync had a performance penalisation associated with using it. It was a bit surprising to see — Nvidia has previously assured me that in that location'southward no performance penalisation for using G-Sync — simply the reports on the Nvidia forums include users with benchmark results comparing G-Sync On to Yard-Sync Off. There are extensive reports and they appointment back for months, including posts in the Nvidia reddit community.

The performance declines reported in the forums appear to be tied to SLI. There's some ambivalence near how long the problem has existed — I've seen some people merits it's tied to drivers released later on the 391.xx family, and others who said the issue has existed for the entire time Nvidia has had Pascal GPUs on the market. The issue is simple: Co-ordinate to posts on Nvidia's forums and in the Nvidia subreddit, activating Thousand-Sync at the same fourth dimension as SLI results in significant performance drops in many games.

SLI is Nvidia's technology for using more than one GPU to render a scene at the same fourth dimension, while G-Sync is a technology that smoothes frame rates compared with standard V-Sync by ensuring that the monitor is synchronized to the GPU'due south refresh charge per unit and presents a frame as quickly as the display is capable of delivering it. And while I can't speculate on exactly what the problem is, we tin intuit a reason: Timing.

Both G-Sync and SLI have major timing implications. Keeping the GPU and monitor running in sync takes time. Moving data from one GPU to another and and then displaying the frames rendered by that same GPU takes time. If yous target a 30fps frame rate, you need to evangelize a new frame every 33.3ms. If you lot want to run at 60fps, that means you demand a new frame every sixteen.6ms. If you target 120fps, that means you need a new frame every 8.3ms. At a sure point, you've got a very limited window with which to work.

That'south our theory, at least, later spending some time exploring this upshot. To showtime, let'due south wait at the results user octiceps posted on the Nvidia forums:

There are some huge drops in this graph. Rising Tempest 2 going from over 200fps to only 75? And so, conversely, there are some very pocket-sized gaps. A 10 percentage driblet in Witcher 3 is still meaning — nobody wants to drop frames — but if we're being honest, it's non a gap you lot'd observe unless you were running a benchmark or knew a specific area with a mammoth frame drop in it.

I decided to test the situation myself with a pair of GTX 1080 GPUs, the highest-end cards I accept in a matched pair. The optics of the issue are pretty bad. While there aren't many SLI owners, much less SLI owners with G-Sync monitors, the few that exist likely represent the biggest consumer spenders in the enthusiast ecosystem. If yous bought into G-Sync a few years ago, yous could easily accept dropped $600 per GTX 1080 (or $700 per 1080 Ti) plus a $500 monitor. Given that the most common Steam Survey configuration is a GTX 1060 paired with a 1080p monitor, these are people dropping serious cash on Nvidia hardware.

Test Setup

At that place's a substantial configuration divergence, I suspect, between the G-Sync monitor nosotros have available and the hardware these enthusiasts are using. The just G-Sync monitor I have is an Acer XB280HK, and while it'south 4K capable, information technology supports a maximum refresh rate of 60Hz. This means that by definition, I can't use G-Sync in tests that hit frame rates higher than 60Hz. If this is a timing issue that only occurs higher up that frame rate, I definitionally won't run across it.

Spoiler warning: It isn't, and I did.

What made this easier to bank check is that our Core i7-8086K testbed we used for the RTX 2080 and 2080 Ti review is still fully assembled. The entire system was a make-new Windows x install with just ane Nvidia driver ever installed (411.63). It'southward a pristine configuration — fifty-fifty the games were downloaded from scratch rather than copying over an archived Steam library.

We tested ii games that were mentioned by enthusiasts every bit being specifically impacted and one title that was not. Our target frame rates were equally close to 60fps as possible without going over it, and we modeled the beliefs of various titles at different resolutions to exam how much the problem appeared or disappeared depending on the GPU's average frame rate. Nosotros also tested a host of other potential variables, including whether G-Sync was ready to fullscreen-but or also active in borderless style, and whether V-Sync was enabled or disabled. We observed no operation differences that weren't otherwise explained past changing V-Sync itself. Nosotros likewise tested to see whether it made a difference to employ DX11 versus DX12 in the titles that supported both.

Nosotros observed no performance impact any from changing G-Sync to operate in borderless fashion versus only fullscreen mode, and we saw no performance modify from changing between V-Sync enabled and V-Sync disabled. Go along in mind we only tested a few games — we were looking for potential evidence of a problem, not trying to perform an exhaustive evaluation of all the weather condition under which G-Sync performance tin vary on 10-fifteen games.

Considering a pair of 1080s is, in some cases, capable of boosting modern games to above 60fps even at 4K, we as well checked games that allow for supersampling. Finally, nosotros ran these tests on both a unmarried GTX 1080 Ti as well as a pair of GTX 1080s. All of the problems we observed announced to be unique to GPUs running in SLI. The 1080 Ti had no trouble in any examination configuration and we saw no deviation between G-Sync enabled and G-Sync disabled when testing one GPU.

Deus Ex: Mankind Divided

Deus Ex: Mankind Divided shows a small-but-definite performance loss when Chiliad-Sync is enabled, as shown below. Interestingly, this gap appears merely in DX11 mode. When we switched to DX12, information technology vanished.

DX-NVData

I can't really hazard a guess as to why, beyond noting that DXMD seems to have a actually odd engine in some respects. The performance hit from activating 4x MSAA rivals what you'd expect from a supersampled antialiasing solution (that'due south the performance hit that anybody tries to avoid considering the cost of rendering a scene in 2x SSAA is equivalent to the performance hit from running it at 2x electric current resolution). If you have a 1080p monitor and a GTX 1080 TiSEEAMAZON_ET_135 See Amazon ET commerce, you lot could run in what'll look just like 4K from cranking 1080p to 2x SSAA, but near games don't offer the option and nigh gamers don't own a GPU powerful enough to accept reward of it in modern titles.

Far Cry 5

Because we accept to go along the frame rate under 60fps at all times to come across the true bear on of turning G-Sync off or on, nosotros tested FC5 in four different resolutions: 4K, 4K+1.1x supersampling, 4K+1.3x supersampling, and 4K+1.5x supersampling. The results and the performance gap betwixt having Chiliad-Sync on versus G-Sync off are shown beneath:

Gsync-FC5

The closer the GPU is running to 60fps, the larger the gaps. As the frame rate decreases, the gap between the ii solutions also decreases. This seems to imply that our timing theory could be right. At the very least, our findings confirm Nvidia forum user's shaunwalsh'southward observation that "running Gsync lowers FPS past 10-20% depending on the championship. I tested this in FC5 and Ghost Recon Wildlands." Our results show that FC5 is between i.09x and 1.20x faster with G-Sync disabled, depending on the resolution target. FC5 does non support DX12, so we were unable to test this style.

Up to this signal, we've seen two distinct findings.

1) Turning on DX12 may eliminate the penalty.
2) The penalty size increases as the frame rate rises.

Got that? Good. We're throwing it out the window.

Hitman (2016)

Hitman wasn't listed as an impacted championship, but I took it for a spin anyway. I'm glad I did. It provided a useful third example in our tests. Hither are our Hitman results in both DX11 and DX12. As with Far Cry, we tested Hitman with i.3x and ane.5x supersampling to push the frame charge per unit completely into our monitor's G-Sync range. This fourth dimension, we had to utilize supersampling at 4K to start with, which is why yous don't see the static "4K" test results.

G-Sync-Hitman

The good news is, you tin can once once more eliminate the DX11 performance penalty associated with using G-Sync and SLI at the same time. The bad news is, you've got to take a 30fps frame charge per unit to do it. In DX11, the functioning striking is a static 1.27x in both supersampling modes. This bucks the trend we saw with FC5 and Deus Ex.

We were unable to benchmark games similar Sleeping Dogs considering nosotros couldn't pull the GPU frame rate down sufficiently to bring it beneath our 60fps requirement. We observed a 2fps difference in this title between having G-Sync enabled and disabled (71 fps versus 73 fps) but that could fall within a reasonable margin of error.

However, the design here is articulate. Turning K-Sync on and using SLI is not guaranteed to tank your frame charge per unit. We also tested Metro Final Light Redux with a forced AFR2 rendering profile, and that game showed no performance drop at all between G-Sync enabled and disabled. Deus Ex Flesh Divided reported a small penalty that vanished in DX12, while Hitman takes too much of a performance hit in that style when using SLI to ever justify information technology. Three games, three different performance models.

It's always dicey to try and test forum reports, not considering forum commenters are liars, but because most don't provide sufficient technical information to exist sure you're reproducing a trouble correctly. I don't have an explanation for this event at the moment and I realize that "timing problem" is extremely vague. Information technology's a theory that happens to fit some mutual-sense facts. Our results collectively suggest that the upshot is real and that the performance gaps could be every bit large every bit Nvidia users say, particularly if they continue to worsen as frame rate increases.

Nvidia Needs to Get in Front end of This

Objectively, this doesn't impact very many people. All available information has always suggested that only a small fraction of Nvidia users purchase SLI, that but a fraction of that fraction tin beget two of the same high-stop GPUsSEEAMAZON_ET_135 See Amazon ET commerce, and that but a fraction of those buyers opted to purchase a Chiliad-Sync monitor on top of that.

But while it may not impact very many people, it very much impacts the people who have poured the most money into Nvidia's products and who represent its biggest fans. If you've got a pair of GTX 1080 Tis and a 1000-Sync monitor, you lot likely spent virtually $2,000 on your GPU and brandish alone. Fifty-fifty a caryatid of GTX 1070s could take run $700 for the pair and another $422 for the cheapest Dell G-Sync display on Newegg. The minimum purchase-in price for this technology is over a grand, bold folks bought at 2022 prices. That'south enough money to buy a new gaming PC, and your top-spending customers are dropping information technology on GPUs. Not taking intendance of your halo customers can be a very expensive mistake, and while there aren't a ton of people talking about this topic on reddit, the conversation threads go back for months. A lot of folks have been both patient and resourceful in trying to collaborate, share data, and notice workarounds.

If Nvidia can't guarantee that SLI will be compatible with 1000-Sync without mild-to-massive operation losses and no fashion to predict in advance what you'll come across, it needs to communicate that fact. It's entirely possible that the complex intersection between game engines, GPUs, and monitors creates situations in which G-Sync tin't be finer employed without a massive performance hitting no matter what Nvidia does. The fact that we come across different performance models from different games suggests that the game engine plays a role here. There'due south also the fact that G-Sync is intended to operate when frame rates are low and it makes its largest deviation in that mode. The higher the frame rate, the smaller the impact of missing a V-Sync refresh cycle. If y'all're playing at 30fps, missing a frame presentation means your current frame is displayed for ~66.6ms. If you play at 120fps, a missed presentation results in a frame repeat for xvi.6ms. Every bit the frame rate rises, the difference between using and not-using G-Sync (or FreeSync) shrinks. At a certain frame charge per unit, you wouldn't exist able to tell the deviation because not enough time has passed for you to observe it.

But if information technology'southward true that SLI and 1000-Sync are more than of a peanut butter-mayonnaise sandwich than a Lead-chocolate combo, that needs to be communicated. That $422 monitor is only a 1440p brandish — and you tin can buy a 4K IPS console without G-Sync for the same corporeality of coin. Or a 21:9 ultra-broad monitor. Or a monitor with FreeSync support, which doesn't come up upward with a premium. You lot get the point.

I don't arraign Nvidia for being unable to fix bug that aren't of its making, or those mandated past the pesky laws of physics. Merely the company owes its customers an explanation for this behavior and an honest update about their ability to solve it, including the fact that it may never exist solved, if that'south the case. The current situation reflects poorly on Nvidia.

For the record, it's entirely possible AMD has this issue also. If it does, the same applies. These are complex capabilities that end-users pay heavy premiums, in some cases, to access. All customers deserve honesty, menses, without exception, but the customers poised to spend thousands of dollars on your products deserve to know whether they're buying marketing claptrap or actual performance.

Now Read: Nvidia RTX 2080 and RTX 2080 Ti Review: You Tin't Smoothen a Turing, Nvidia RTX Ray Tracing Is Incredibly Expensive in Remedy'south Northlight Engine Demo, and Nvidia's RTX 2070 Features 2022 Functioning, Currently Useless Features, and a Massive Price Increment