The AMD FreeSync Review
by Jarred Walton on March 19, 2015 12:00 PM ESTFreeSync Features
In many ways FreeSync and G-SYNC are comparable. Both refresh the display as soon as a new frame is available, at least within their normal range of refresh rates. There are differences in how this is accomplished, however.
G-SYNC uses a proprietary module that replaces the normal scaler hardware in a display. Besides cost factors, this means that any company looking to make a G-SYNC display has to buy that module from NVIDIA. Of course the reason NVIDIA went with a proprietary module was because adaptive sync didn’t exist when they started working on G-SYNC, so they had to create their own protocol. Basically, the G-SYNC module controls all the regular core features of the display like the OSD, but it’s not as full featured as a “normal” scaler.
In contrast, as part of the DisplayPort 1.2a standard, Adaptive Sync (which is what AMD uses to enable FreeSync) will likely become part of many future displays. The major scaler companies (Realtek, Novatek, and MStar) have all announced support for Adaptive Sync, and it appears most of the changes required to support the standard could be accomplished via firmware updates. That means even if a display vendor doesn’t have a vested interest in making a FreeSync branded display, we could see future displays that still work with FreeSync.
Having FreeSync integrated into most scalers has other benefits as well. All the normal OSD controls are available, and the displays can support multiple inputs – though FreeSync of course requires the use of DisplayPort as Adaptive Sync doesn’t work with DVI, HDMI, or VGA (DSUB). AMD mentions in one of their slides that G-SYNC also lacks support for audio input over DisplayPort, and there’s mention of color processing as well, though this is somewhat misleading. NVIDIA's G-SYNC module supports color LUTs (Look Up Tables), but they don't support multiple color options like the "Warm, Cool, Movie, User, etc." modes that many displays have; NVIDIA states that the focus is on properly producing sRGB content, and so far the G-SYNC displays we've looked at have done quite well in this regard. We’ll look at the “Performance Penalty” aspect as well on the next page.
One other feature that differentiates FreeSync from G-SYNC is how things are handled when the frame rate is outside of the dynamic refresh range. With G-SYNC enabled, the system will behave as though VSYNC is enabled when frame rates are either above or below the dynamic range; NVIDIA's goal was to have no tearing, ever. That means if you drop below 30FPS, you can get the stutter associated with VSYNC while going above 60Hz/144Hz (depending on the display) is not possible – the frame rate is capped. Admittedly, neither situation is a huge problem, but AMD provides an alternative with FreeSync.
Instead of always behaving as though VSYNC is on, FreeSync can revert to either VSYNC off or VSYNC on behavior if your frame rates are too high/low. With VSYNC off, you could still get image tearing but at higher frame rates there would be a reduction in input latency. Again, this isn't necessarily a big flaw with G-SYNC – and I’d assume NVIDIA could probably rework the drivers to change the behavior if needed – but having choice is never a bad thing.
There’s another aspect to consider with FreeSync that might be interesting: as an open standard, it could potentially find its way into notebooks sooner than G-SYNC. We have yet to see any shipping G-SYNC enabled laptops, and it’s unlikely most notebooks manufacturers would be willing to pay $200 or even $100 extra to get a G-SYNC module into a notebook, and there's the question of power requirements. Then again, earlier this year there was an inadvertent leak of some alpha drivers that allowed G-SYNC to function on the ASUS G751j notebook without a G-SYNC module, so it’s clear NVIDIA is investigating other options.
While NVIDIA may do G-SYNC without a module for notebooks, there are still other questions. With many notebooks using a form of dynamic switchable graphics (Optimus and Enduro), support for Adaptive Sync by the Intel processor graphics could certainly help. NVIDIA might work with Intel to make G-SYNC work (though it’s worth pointing out that the ASUS G751 doesn’t support Optimus so it’s not a problem with that notebook), and AMD might be able to convince Intel to adopt DP Adaptive Sync, but to date neither has happened. There’s no clear direction yet but there’s definitely a market for adaptive refresh in laptops, as many are unable to reach 60+ FPS at high quality settings.
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SleepModezZ - Thursday, March 19, 2015 - link
Really different reviews between AnandTech and PC Perspective. You conclude that FreeSync performs as well as G-Sync - if not better, because of the option to disable V-sync. PC Perspective, on the other hand, noticed that their FreeSync monitors performed badly compared to the G-Sync monitors when the frame rate dropped below the lowest refresh rate of the monitor.You give the impression that they would behave the same - or FreeSync would be potentially better because you could choose your poison: stutter or tearing - when with G-Sync you would always get stuttering. PC Perspective, on the other hand, tells that G-Sync monitors handle this gracefully by refreshing the display twice or more during those longer frames - and as such G-Sync avoids both stutter and tearing at those lower fram rates. Their FreeSync monitors did not do that - and the stuttering or tearing was very noticeable. The frame rate dropping below 48 fps is not uncommon and the displays behavior in those situations is very important. That makes the G-Sync the superior technology. Unless - the tearing or stuttering at speeds lower than the display's lowest refresh rate is only a problem with that specific monitor and not with the FreeSync / AdaptiveSync technology in general. (The LG monitor is incapable of doubling its slowest refresh rate - other monitors that are capable maybe could handle the situation differently. If not, FreeSync is the inferior technology.)
I don't know how G-Sync and FreeSync actually would handle full screen movies at 24 fps. G-Sync could easily display it at a 48 Hz refresh rate. Your LG monitor would probably also show it at 48 Hz - because it is the lowest it could go. But would the LG monitor with FreeSync be smart enough to show a 25 fps movie in 50 Hz - or would it display it in 48 Hz with unnecessary tearing or stuttering?
Gigaplex - Friday, March 20, 2015 - link
"PC Perspective, on the other hand, tells that G-Sync monitors handle this gracefully by refreshing the display twice or more during those longer frames - and as such G-Sync avoids both stutter and tearing at those lower fram rates."That would drastically reduce the effects of tearing, but it would not do much, if anything, for stutter.
SleepModezZ - Friday, March 20, 2015 - link
It would reduce stutter in the sense that if the frame rate were, for example, constantly 30 fps, G-sync would give you every frame when it is ready - keeping the motion fluid. FreeSync with V-SYnc on, on the other hand, would force that into the lowest refresh rate of the monitor. It would double some frames and not others - making the timing of the frames different and making a constant 30 fps motion jerky where G-Sync would not. I would call that jerky motion 'stutter' - FreeSync (currently) has it, G-Sync does not.In short, G-Sync retains its variable refresh rate technology when going under the displays min refresh rate. FreeSync does not but switches to constant refresh rate at the monitors min refresh rate - introducing either tearing or stutter. Within the display's refresh rate range they perform the same. When going faster than the refresh rate range - FreeSync gives the option of disabling V-Sync and choosing tearing instead of stuttering. There it is better. I just think that the low fps range is probably more important than the high. I would not buy any FreeSync / Adaptive Sync displays before they demonstrate that they can handle those low fps situations as gracefully as G-Sync does.
WatcherCK - Thursday, March 19, 2015 - link
TFTcentral have done a review of the soon to be released Acer monitor:http://www.tftcentral.co.uk/reviews/acer_xb270hu.h...
And as Ryan said it is a beast, but one question you buy an XB270hu and you plug in your 290x, because the video card doesnt support GSYNC uses the standard scaler? in the Acer to display video data. Now if the Acer uses a scaler from one of the four main manufacturers listed in the article is there a chance it would support Freesync? (Acer wouldnt advertise that obviously since the monitor is a GSYNC branded monitor....)
So there are a few assumptions above about the operations of GSYNC, but Im curious if this will be the case as it keeps red and green camps happy...
One other question if anyone is happy to answer, high hertz refresh monitors will they maintain their peak capable refresh when in portrait mode or are they limited to a lower refresh rate or GSYNC for that matter? Im thinking a triple monitor portrait setup for my next build.
cheers
sonicmerlin - Thursday, March 19, 2015 - link
Will Freesync work with the current gen consoles?SleepModezZ - Thursday, March 19, 2015 - link
No.Adaptive Sync is a Display Port specific standard. What current gen console supports Display Port? None to my knowledge. HDMI is a different standard and I don't think there have been even any rumors about putting adaptive sync technology into the HDMI standard. And if it some day would come - would the current HDMI hardware on the consoles be able to support it after a driver update from AMD? Probably not.
Murloc - Thursday, March 19, 2015 - link
it's not likely to happen any time soon since video and STBs etc. revolve around the usual framerates and TVs do the same so there's no need for this kind of flexibility, tearing is not an issue.Too bad that TV standards like HDMI spill over in the computer world (audio, projectors, laptops, etc.) and hamstring progress.
sonicmerlin - Friday, March 20, 2015 - link
Well what if MS and Sony released hardware refreshes (like a slimmed down PS4) that included display port?Gigaplex - Friday, March 20, 2015 - link
I'm pretty sure that both Xbox One and PS4 use GCN 1.0 hardware, so no, a DisplayPort refresh probably wouldn't help.Norseman4 - Thursday, March 19, 2015 - link
Can you please verify some information:On the specs page for the BenQ XL2730Z (http://gaming.benq.com/gaming-monitor/xl2730z/spec... it states a 54Hz min vertical refresh. This could be a copy/paste issue since it's the same as the min horizontal refresh.