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The G-Sync experience
Welp, they've done it. That's my summation of the G-Sync experience. Asus and Nvidia have managed to bring variable refresh technology to the market in a working and seemingly well-refined form—and it works like gangbusters. (Although, really, who are these gangbusters, and why do they get so much credit?) We've already talked about the theory behind G-Sync. I could wear my keycaps thin trying to describe the subject experience of using it, but you really do have to try it for yourself in order to appreciate it fully.

In games, everything that happens onscreen with G-Sync is more immediate, more fluid. As with a lot of game-changing technologies, adjusting to it isn't hard. My son Nathan and I both had the same experience: you sit down in front of the screen, you use it, and periodically throughout the gaming session, you say to yourself, "Wow, this really is smoother." Then any thoughts of monitor technology mostly just disappear, and you're better able to concentrate on the game.

The hard part is going back to gaming on a 60Hz monitor afterwards. My immediate reaction was, "This is broken somehow." I was briefly perplexed, but then I realized: I was not wrong. G-Sync has just fixed an incredibly long-standing problem.

There's no good way to transmit the G-Sync experience over the intarwebs for display on conventional monitors. What I can do is record what happens onscreen with a high-speed camera and replay the results in slow-motion. I've already posted comparisons from a whole range of sync modes and refresh rates using early G-Sync hardware right here, so go look at those if you want an extensive set of examples. For today, let's focus on the PG278Q running G-Sync at a 144Hz peak refresh rate versus a conventional 60Hz vsync setup, since that's probably the comparison most folks will find relevant. We've taken an example from Guild Wars 2, recorded it at 240 FPS, and turned it into a side-by-side video that should illustrate the differences nicely.

With G-Sync at 144Hz, the on-screen animation advances more often and in smaller increments, as expected.  Also, crucially, the content of each of those updates fits with when the update takes place. Each new frame advances the scene's rotation the appropriate amount for when it's painted. Not only are the updates on the 60Hz vsync side less frequent, but some of them seem "off" a little in terms of timing, too. That fact contributes to a kind of lurching, loping sense of advancing motion.

At full speed, these differences are subtler in some ways, since fast updates cure a lot of ills. The overall added goodness of G-Sync seems even more pronounced, though, when your eye is fooled into seeing constant movement rather than a series of individual frames. Paradoxical, maybe, but that's my sense of it.

There's also a distinct sense of solidity with G-Sync that's not present at any refresh rate with vsync disabled. The utter lack of tearing on the display is very welcome.

Making use of G-Sync at a full 144Hz does involve a bit of fuss. You have to enable it via a checkbox in the Nvidia control panel, and then you have to go to the 3D gaming settings section and choose G-Sync as the display refresh mode. Most games make better use of G-Sync if you set "preferred refresh rate" to "highest available" in that same menu. This option circumvents some of the FPS caps built into a lot of PC titles. In other cases, you may have to dig into config files in order to remove the FPS limit.

Getting rid of the FPS caps can cause problems in some games, too. The physics in Skyrim go hilariously sideways at high frame rates, for instance. If you've been playing with uncapped frame rates and vsync disabled like I have for ages, though, all of this fuss will be familiar territory. Fortunately, for the majority of games, you can just set vsync to "off" in their video settings menu and you're good to go.

Alternative goodness: low-persistence mode
The PG278Q has another interesting display mode, in addition to G-Sync, known as ultra-low motion-blur or ULMB. This bit of dark magic exists separately from G-Sync and, unfortunately, can't be used in conjunction with it. You have to disable G-Sync in the Nvidia control panel and set the display refresh rate to 120Hz or less in order to enable ULMB mode. Also, as far as I can tell, ULMB only works with GeForce graphics cards.

Once it's working, ULMB mode attempts to reduce motion blur by modifying the backlight behavior. Specifically, the backlight cycles off while the display is being updated and then pulses on once each new frame is completely painted. This strobing effect reduces the overall brightness of the backlight somewhat, but it's otherwise imperceptible to human eyes. I didn't notice any flicker with the display strobing at 120Hz.

This low-persistence display method is a well-known trick for reducing motion blur that's even been deployed in the latest prototypes of the Oculus Rift. And it works. Everything from scrolling text to in-game action is affected by the change, with added clarity and sharper object edges in each case.

I tried to capture the impact of the ULMB mode using my high-speed camera at 240 FPS, but what I got instead was a recording of the strobing in action. Check it out. The video starts in the regular backlight mode, and part-way through, I enable ULMB instead. You'll notice when it happens.

Fortunately, it doesn't look like such a train wreck to human eyes.

In fact, the strobing isn't at all obvious in this next video recorded at 120 FPS, and I think maybe it kind of captures some of the additional clarity—although honestly, the focus isn't great, and the benefits are much easier to perceive in person. Again, we start in regular mode and then switch to ULMB.

Yeah, so make what you will of that, I guess. You've really gotta see it with your own eyes. Some of the BlurBusters demos with scrolling texts and animated objects reveal dramatic improvements.

I probably need to spend more time gaming with ULMB mode enabled in order to appreciate it fully. My sense is that it's an improvement, but it doesn't have the same visceral impact as G-Sync's variable refresh rates do. If I had to pick—and the PG278Q essentially forces you to—I'd choose G-Sync for gaming with no regrets. Still, ULMB mode adds something different to the mix, and it hints at a possible future where low-persistence modes might be combined with variable refresh rates, if such a thing becomes feasible.