Game Compatibility: Mostly Great
Going Hands-On With More Games
I tried testing several other titles. Crysis 3, Tomb Raider, Skyrim, BioShock: Infinite, Battlefield 4 all received at least some time on the bench. All of them except Skyrim saw some benefit from G-Sync. The impact varies by title, but once you see it, you cannot ignore what was going on previously that you were subconsciously disregarding.
There can be artifacts. For example, the crawling attributed to aliasing is more distracting when motion is smooth. So you end up really wanting as much AA as you can get to keep your eyes from being drawn to jaggies that weren't as bothersome before.
Skyrim: A Special Case
As for Skyrim, the Creation engine is designed with V-sync enabled by default. It takes a special iPresentInterval=0 line added to one of the game's .ini files in order for us to benchmark it above 60 FPS.
So, there are three ways to try testing Skyrim: in its default state, leaving Nvidia's driver at "Use the 3D application setting", forcing G-Sync on in the driver and leaving Skyrim alone, and then forcing G-Sync on and disabling V-sync through Skyrim's .ini.
With the prototype monitor set to 60 Hz, the first configuration predictably yielded a flat 60 FPS at Ultra settings using a GeForce GTX 770. Consequently, motion is nice and smooth. However, user input is still hampered by an obnoxious amount of lag. Moreover, strafing from side to side reveals lots of motion blur. This is the way almost everyone plays the game on PCs, though. You can step the screen up to 144 Hz of course, and that really cleans up the motion blur. But because the GTX 770 sits between 90 and 100 FPS, you end up with palpable stuttering as the engine jumps between 144 and 72 FPS.
At 60 Hz, adding G-Sync to the equation actually has a detrimental effect, likely because V-sync is forced on and the technology is meant to operate with V-sync off. Now, strafing (particularly up close to walls) leads to fairly severe stuttering. That's going to be a problem on 60 Hz G-Sync-capable panels, at least in games like Skyrim. Fortunately, as it pertains to Asus' VG248Q, you can switch to 144 Hz and, despite V-sync still being on, G-Sync appears to function at those high frame rates without stutter.
Completely shutting off V-sync makes mouse control so much snappier in Skyrim. However, you do end up with a bunch of tearing (not to mention other artifacts like shimmering water). Turning on G-Sync still leaves you with stutters at 60 Hz, which smooth out at 144 Hz. Although we do all of our testing with V-sync turned off for our graphics card reviews, I wouldn't recommend playing this game without it.
For Skyrim, turning G-Sync off and playing at 60 Hz is probably the most natural approach, providing you get more than 60 FPS all of the time using your desired quality settings (not difficult).
What the hell is Mantle?
I applaud the advancement, but I have a perfectly functional 26 inch monitor and don't want to have to buy another one AND a compatible GPU just to stop tearing.
At that point I'm looking at $400 to $600 for a relatively paltry gain. If it comes standard on every monitor, I'll reconsider.
Is it great for those who already happen to fall within the requirements? Sure, but unless Nvidia opens this up or competitors make similar solutions, I feel like this is doomed to be as niche as lightboost, Physx, and, I suspect, Mantle.
Tearing and input lag at 60Hz on a 2560x1440 or 2560x1600 has been the only reason I won't game on one. G-sync will get me there.
This is awesome, outside-of-the-box thinking tech.
I do think Nvidia is making a huge mistake by keeping this to themselves though. This should be a technology implemented with every panel sold and become part of an industry standard for HDTVs, monitors or other viewing solutions! Why not get a licensing payment for all monitors sold with this tech? Or all video cards implementing this tech? It just makes sense.
You mention it being smooth when set to 144hz with Gsync, is there any way you cap the display at 64hz and try it with Gsync alone (iPresentinterval=0) and see what happens then? Just wondering if the game is at fault here and if that specific issue is still there in their latest version of the engine.
Alternatively I suppose you could load up Fallout 3 or NV instead and see if the Gsync results match Skyrim.