It's more than just a branding issue
As a part of my look at the first wave of AMD FreeSync monitors hitting the market, I wrote an analysis of how the competing technologies of FreeSync and G-Sync differ from one another. It was a complex topic that I tried to state in as succinct a fashion as possible given the time constraints and that the article subject was on FreeSync specifically. I'm going to include a portion of that discussion here, to recap:
First, we need to look inside the VRR window, the zone in which the monitor and AMD claims that variable refresh should be working without tears and without stutter. On the LG 34UM67 for example, that range is 48-75 Hz, so frame rates between 48 FPS and 75 FPS should be smooth. Next we want to look above the window, or at frame rates above the 75 Hz maximum refresh rate of the window. Finally, and maybe most importantly, we need to look below the window, at frame rates under the minimum rated variable refresh target, in this example it would be 48 FPS.
AMD FreeSync offers more flexibility for the gamer than G-Sync around this VRR window. For both above and below the variable refresh area, AMD allows gamers to continue to select a VSync enabled or disabled setting. That setting will be handled as you are used to it today when your game frame rate extends outside the VRR window. So, for our 34UM67 monitor example, if your game is capable of rendering at a frame rate of 85 FPS then you will either see tearing on your screen (if you have VSync disabled) or you will get a static frame rate of 75 FPS, matching the top refresh rate of the panel itself. If your game is rendering at 40 FPS, lower than the minimum VRR window, then you will again see the result of tearing (with VSync off) or the potential for stutter and hitching (with VSync on).
But what happens with this FreeSync monitor and theoretical G-Sync monitor below the window? AMD’s implementation means that you get the option of disabling or enabling VSync. For the 34UM67 as soon as your game frame rate drops under 48 FPS you will either see tearing on your screen or you will begin to see hints of stutter and judder as the typical (and previously mentioned) VSync concerns again crop their head up. At lower frame rates (below the window) these artifacts will actually impact your gaming experience much more dramatically than at higher frame rates (above the window).
G-Sync treats this “below the window” scenario very differently. Rather than reverting to VSync on or off, the module in the G-Sync display is responsible for auto-refreshing the screen if the frame rate dips below the minimum refresh of the panel that would otherwise be affected by flicker. So, in a 30-144 Hz G-Sync monitor, we have measured that when the frame rate actually gets to 29 FPS, the display is actually refreshing at 58 Hz, each frame being “drawn” one extra instance to avoid flicker of the pixels but still maintains a tear free and stutter free animation. If the frame rate dips to 25 FPS, then the screen draws at 50 Hz. If the frame rate drops to something more extreme like 14 FPS, we actually see the module quadruple drawing the frame, taking the refresh rate back to 56 Hz. It’s a clever trick that keeps the VRR goals and prevents a degradation of the gaming experience. But, this method requires a local frame buffer and requires logic on the display controller to work. Hence, the current implementation in a G-Sync module.
As you can see, the topic is complicated. So Allyn and I (and an aging analog oscilloscope) decided to take it upon ourselves to try and understand and teach the implementation differences with the help of some science. The video below is where the heart of this story is focused, though I have some visual aids embedded after it.
Still not clear on what this means for frame rates and refresh rates on current FreeSync and G-Sync monitors? Maybe this will help.
What is FreeSync?
FreeSync: What began as merely a term for AMD’s plans to counter NVIDIA’s launch of G-Sync (and mocking play on NVIDIA’s trade name) has finally come to fruition, keeping the name - and the attitude. As we have discussed, AMD’s Mantle API was crucial to pushing the industry in the correct and necessary direction for lower level APIs, though NVIDIA’s G-Sync deserves the same credit for recognizing and imparting the necessity of a move to a variable refresh display technology. Variable refresh displays can fundamentally change the way that PC gaming looks and feels when they are built correctly and implemented with care, and we have seen that time and time again with many different G-Sync enabled monitors at our offices. It might finally be time to make the same claims about FreeSync.
But what exactly is FreeSync? AMD has been discussing it since CES in early 2014, claiming that they would bypass the idea of a custom module that needs to be used by a monitor to support VRR, and instead go the route of open standards using a modification to DisplayPort 1.2a from VESA. FreeSync is based on AdaptiveSync, an optional portion of the DP standard that enables a variable refresh rate courtesy of expanding the vBlank timings of a display, and it also provides a way to updating EDID (display ID information) to facilitate communication of these settings to the graphics card. FreeSync itself is simply the AMD brand for this implementation, combining the monitors with correctly implemented drivers and GPUs that support the variable refresh technology.
A set of three new FreeSync monitors from Acer, LG and BenQ.
Fundamentally, FreeSync works in a very similar fashion to G-Sync, utilizing the idea of the vBlank timings of a monitor to change how and when it updates the screen. The vBlank signal is what tells the monitor to begin drawing the next frame, representing the end of the current data set and marking the beginning of a new one. By varying the length of time this vBlank signal is set to, you can force the monitor to wait any amount of time necessary, allowing the GPU to end the vBlank instance exactly when a new frame is done drawing. The result is a variable refresh rate monitor, one that is in tune with the GPU render rate, rather than opposed to it. Why is that important? I wrote in great detail about this previously, and it still applies in this case:
The idea of G-Sync (and FreeSync) is pretty easy to understand, though the implementation method can get a bit more hairy. G-Sync (and FreeSync) introduces a variable refresh rate to a monitor, allowing the display to refresh at wide range of rates rather than at fixed intervals. More importantly, rather than the monitor dictating what rate this refresh occurs at to the PC, the graphics now tells the monitor when to refresh in a properly configured G-Sync (and FreeSync) setup. This allows a monitor to match the refresh rate of the screen to the draw rate of the game being played (frames per second) and that simple change drastically improves the gaming experience for several reasons.
Gamers today are likely to be very familiar with V-Sync, short for vertical sync, which is an option in your graphics card’s control panel and in your game options menu. When enabled, it forces the monitor to draw a new image on the screen at a fixed interval. In theory, this would work well and the image is presented to the gamer without artifacts. The problem is that games that are played and rendered in real time rarely fall into a very specific frame rate. With only a couple of exceptions, games frame rates will fluctuate based on the activity happening on the screen: a rush of enemies, a changed camera angle, an explosion or falling building. Instantaneous frame rates can vary drastically, from 30, to 60, to 90, and force the image to be displayed only at set fractions of the monitor's refresh rate, which causes problems.
Subject: Displays, Shows and Expos | January 8, 2015 - 12:13 AM | Ryan Shrout
Tagged: vrr, video, variable refresh rate, mg279q, gsync, g-sync, freesync, ces 2015, CES, asus
We have talked about G-Sync for what seems like years now and we got our first hands-on with AMD's FreeSync monitors earlier this week at CES, but the new ASUS MG279Q is in an interesting place: it is the first display that publicly supports Adaptive Sync and DP 1.2a+ but does not have an affiliation with either branded variable refresh rate technology. As it turns out though, that isn't bad news.
First, let's talk about the hardware. The screen is a 27-in 2560x1440 display with IPS panel technology and a maximum refresh rate of 120 Hz. High refresh rate IPS monitors are brand new and we are glad to see that ASUS is bringing one to the market so we can finally combine great color, great viewing angles and great refresh rates. The monitor supports DP 1.2a+ and Adaptive Sync which leads us too...
...the fact that this monitor will work with AMD Radeon graphics cards and operate at a variable refresh rate. After talking with AMD's Robert Hallock at the show, he confirmed that AMD will not have a whitelist/blacklist policy for FreeSync displays and that as long as a monitor adheres to the standards of DP 1.2a+ then they will operate in the variable refresh rate window as defined by the display's EDID.
So, as described by the ASUS reps on hand, this panel will have a minimum refresh of around 40 Hz and a maximum of 120 Hz, leaving a sizeable window for variable refresh to work it's magic.
Even better? The price! ASUS said this panel will ship in late Q1 of this year for just $599!
Follow all of our coverage of the show at http://pcper.com/ces
Subject: Graphics Cards | October 18, 2013 - 10:52 AM | Ryan Shrout
Tagged: variable refresh rate, refresh rate, nvidia, gsync, geforce, g-sync
UPDATE: I have posted a more in-depth analysis of the new NVIDIA G-Sync technology: NVIDIA G-Sync: Death of the Refres Rate. Thanks for reading!!
UPDATE 2: ASUS has announced the G-Sync enabled version of the VG248QE will be priced at $399.
During a gaming event being held in Montreal, NVIDIA unveield a new technology for GeForce gamers that the company is hoping will revolutionize the PC and displays. Called NVIDIA G-Sync, this new feature will combine changes to the graphics driver as well as change to the monitor to alter the way refresh rates and Vsync have worked for decades.
With standard LCD monitors gamers are forced to choose between a tear-free experience by enabling Vsync or playing a game with the substantial visual anomolies in order to get the best and most efficient frame rates. G-Sync changes that by allowing a monitor to display refresh rates other than 60 Hz, 120 Hz or 144 Hz, etc. without the horizontal tearing normally associated with turning off Vsync. Essentially, G-Sync allows a properly equiped monitor to run at a variable refresh rate which will improve the experience of gaming in interesting ways.
This technology will be available soon on Kepler-based GeForce graphics cards but will require a monitor with support for G-Sync; not just any display will work. The first launch monitor is a variation on the very popular 144 Hz ASUS VG248QE 1920x1080 display and as we saw with 3D Vision, supporting G-Sync will require licensing and hardware changes. In fact, NVIDIA claims that the new logic inside the panels controller is NVIDIA's own design - so you can obviously expect this to only function with NVIDIA GPUs.
DisplayPort is the only input option currently supported.
It turns out NVIDIA will actually be offering retrofitting kits for current users of the VG248QE at some yet to be disclosed cost. The first retail sales of G-Sync will ship as a monitor + retrofit kit as production was just a bit behind.
Using a monitor with a variable refresh rates allows the game to display 55 FPS on the panel at 55 Hz without any horizontal tearing. It can also display 133 FPS at 133 Hz without tearing. Anything below the 144 Hz maximum refresh rate of this monitor will be running at full speed without the tearing associated with the lack of vertical sync.
The technology that NVIDIA is showing here is impressive when seen in person; and that is really the only way to understand the difference. High speed cameras and captures will help but much like 3D Vision was, this is a feature that needs to be seen to be appreciated. How users will react to that road block will have to be seen.
Features like G-Sync show the gaming world that without the restrictions of console there is quite a bit of revolutionary steps that can be made to maintain the PC gaming advantage well into the future. 4K displays were a recent example and now NVIDIA G-Sync adds to the list.
Be sure to stop back at PC Perspective on Monday, November 21st at 2pm ET / 11am PT as we will be joined in-studio by NVIDIA's Tom Petersen to discuss G-Sync, how it was developed and the various ramifications the technology will have in PC gaming. You'll find it all on our PC Perspective Live! page on Monday but you can sign up for our "live stream mailing list" as well to get notified in advance!