AMD FreeSync First Impressions and Technical Discussion

Gaming Experience with FreeSync – LG 34UM67 and BenQ XL2730Z

Our ghosting testing of the BenQ XL2730Z  FreeSync display has been updated after a firmware update. See this article for updated information and video.

Before having to leave for a work-related trip this week I got to spend two full days with the 34UM67 monitor from LG, the first functional FreeSync monitor to make it to our office. This display is unique with a 21:9 aspect ratio and a 2560×1080 resolution all built into an ultra-wide 34-in IPS screen. Available soon with an MSRP of $649, the 34UM67 has a dynamic refresh rate range of 48-75 Hz.

Let’s talk about that first: the 48-75 Hz range, with the 75 Hz being the limit of this panel, is rather narrow. That only gives us a 26 Hz window where the variable frame rate capability of FreeSync can actually work and function. When you game runs at 75 FPS or above, and at 48 FPS and below, you are no longer seeing the benefits of tear-free and stutter-free gaming and instead are going to be forced to use the VSync on/off settings that we discussed above. Why is this range so narrow? This is partly due to the implementation of FreeSync on an IPS panel, something we haven’t actually had hands on with from G-Sync compatible products yet. Also, the 2560×1080 screen is fairly low production and a 75 Hz maximum refresh is actually a step above what we have seen for 21:9 monitors in the past year.

AMD is working on other panels including two 2560×1440 options from BenQ and Acer that work in a 40-144 Hz VRR window, giving the game more room to see the benefits of variable refresh.

The LG 34UM67 34-in 2560×1080 FreeSync monitor

But let’s focus back on the 34UM67 specific as that is where I spent the majority of my time last week. The 34-in screen is impressive to see in person and the IPS configuration means you get great viewing angles – especially important considering the ultra-wide design that creates unique angles even in a normal usage scenario. Using the monitor in a desktop and productivity environment is superb – 21:9 monitors are definitely unique and provide some interesting benefits and caveats for users. More on that later.

But you’re all here to talk about the gaming implications of this monitor and the FreeSync technology implementation. First, let’s focus on the good news: the gaming experience of the variable frame rate when operating inside the 48-75 Hz window is pretty much perfect and matches the experiences we have had with G-Sync. When playing games like Crysis 3 or Metro: Last Light at 55-70 FPS, which is a common frame rate given the settings we were using at the 2560×1080 resolution, the games ran smoothly and we didn’t experience stutter or horizontal tearing that you would normally see with a typical vertical sync configuration. It’s obviously a bit of a disappointment that the range on this panel is so constricted, but when you are operating in that 26 Hz range, the experience was flawless.

When running games over the 75 Hz maximum refresh rate you have the option to enable or disable VSync through the normal methods. When playing a game that is running at consistently higher than 75 FPS the operation is basically unchanged from what you have seen and used before. You will either get a moderate amount of screen tearing depending on the rate matching between the 75 Hz maximum refresh rate of the panel and the actual render rate of the game, or you will see a maximum render rate of 75 FPS if VSync is turned on.

Our next guest, the BenQ XL2730Z 27-in 2560×1440 144 Hz FreeSync Monitor

The result at the lower experience zone is similar but with some more complication. As we played Crysis 3 with the settings jacked up and moved to locations where frame rates dropped below 48 FPS, which is pretty often honestly, we saw the same type of concerns that have plagued monitors for decades. If you had VSync off I saw frequent screen tearing but if you had VSync on you were often experiencing the stutter and judder effects of having a mismatched frame rate and refresh rate. And because the minimum variable refresh rate is 48 FPS, and probably the worst judder comes within the 35-45 FPS range on a monitor with this configuration.

AMD sees some of this as an issue of flexibility and of options for the gamer. With G-Sync today you do not get the option to enable or disable VSync when outside the variable refresh range. At the high end that means that NVIDIA today forces users into a VSync on state, something that many competitive gamers don’t approve of. AMD’s implementation allows those gamers to disable VSync, giving them the lowest possible input latency, highest possible frame rates though at the cost of re-introducing screen tearing. That just happens to be a choice that many gamers would make.

As it turns out, NVIDIA is starting to recognize this as a concern for some users and will  hopefully consider enabling the option to set VSync off when gaming above the maximum panel refresh rate in a future driver.

But on the low side there is really no reason to WANT to have either tearing or stutter unless the implication is that performance is lost or latency is increased with G-Sync. NVIDIA’s implementation today is superior when you are working under the minimum panel refresh, using the embedded controller and module in the panel to force frame multiplication at certain frame rates. And as it turns out, the transition between a variable refresh rate that is smooth and consistent to a tearing or stuttering frame rate (depending on the VSync setting) can be quite jarring if it happens frequently. We found an area in Assassin’s Creed Unity for example that by simply running across the rooftops to a mission marker would push frame rates between 35 FPS and 60 FPS, often crossing that 48 Hz minimum VRR window. When it makes the transition the effect is immediate and I think that some gamers will like that even less than normal stutter or tearing options. Obviously the ideal scenario would be to game ONLY inside that VRR window on FreeSync displays, but that seems unlikely in this case.

It’s fair to assume that the FreeSync experience we got with the LG 34UM67 is probably the worst monitor to start with, as its narrow window of variable refresh more easily brings the complications of FreeSync to light. That is not a slight on the LG monitor itself, it is doing what it can based on the IPS panel technology that it has access to. With the Acer or BenQ monitor that each use a TN 40-144 Hz panel, you get a much larger window of variable refresh rates and thus are you going to see the issues presented by the outside experience zones much less frequently. We have the BenQ monitor in-house as well and I’ll be spending more time with it in the next handful of days for an updated FreeSync story.

Speaking of other models, AMD has eight monitor models that are FreeSync approved that are either shipping now or will be shipping within the next couple of weeks.

Acer and BenQ will have 40-144 Hz TN panels option, LG has a 34-in and 29-in 2560×1080 resolution option, Nixeus and Viewsonic have 144 Hz 1920×1080 options and Samsung will be shipping a pair of 4K options with a maximum refresh rate of 60 Hz with screen sizes ranging from 24-in to 32-in. I don’t all the information for all of these monitors yet but that is a great range of products for initial release. Most of the emphasis from AMD is coming on the 2560×1440 and 2560×1080 models based simply on the demand from users. The Acer XG270HU will ship with a starting MSRP of just $499, $100 less than that matching G-Sync monitor from Acer. The BenQ option will sell for $599 MSPR, though I see it showing up on Amazon.com already with a price tag of $629. Consider that the most popular G-Sync monitor, the ASUS ROG Swift PG278Q, currently sells for $760, it appears that FreeSync monitors will sell for a lower price than G-Sync. How long that lasts will be the most interesting question: I have often hoped that competition in the VRR display market will drive all prices down.

This shows another point in favor of AMD's FreeSync implementation: a wide and varying array of display options. Because the standard is open and can be adopted by vendors using different scalers and controllers, at different resolutions and panel technologies, AMD already has a more varied collection of displays supporting its variable refresh technology than NVIDIA has with G-Sync. I expect that trend will continue as well, with FreeSync showing up in all kinds of display shapes and sizes thanks to the lower barrier to entry of implementation.

The current driver released today to support FreeSync monitors that are already shipping adds VRR support for most Radeon GPUs on the market today. The Radeon R9 295X2, R9 290X, R9 290, R9 285, R7 260X and R7 260 all support FreeSync, though the R9 280X/280 and R9 270X/270, as well as the entirety of the HD 7000-series does not. That is not an arbitrary designation on AMD’s part but instead is a silicon limitation as the display controller in Southern Islands does not support dynamic switching. Obviously all future GPUs will support VRR technology.

CrossFire support isn’t included for any GPUs today though AMD is promising another driver update next month that will include it – apparently making sure that all the frame pacing work that went into the driver over the last 2 years is properly implemented and functional with FreeSync took a bit longer than expected.

Ghosting Concerns

With the two working FreeSync monitors we have been testing over the past week or so we did notice ghosting of the animated images was prevalent. Our first monitor was the LG 34UM67, an IPS display, and thus we actually expected a bit more ghosting than our comparable 144 Hz TN panels. But we actually see a similar effect with the BenQ 144 Hz TN FreeSync monitor as well.

You can see an animated GIF implementation of this side-by-side as well.

Also, because these were filmed in the high speed mode of an iPhone 6, don't consider the slow draw rate that appears to be stutter in the animations. The point is to focus on the ghosting concerns.

While I was away at GTC, Allyn did some more work looking into and exploring the ghosting we saw on the FreeSync monitors. In the animation above you can see three different displays at work, all using the AMD FreeSync demo of a windmill rotating and also panning on the screen. On the left is the G-Sync enabled ASUS PG278Q ROG Swift at 144 Hz refresh rate; in the middle is the BenQ XL2730Z 144 Hz monitor and on the right is the LG 34UM67 at 75 Hz. The animation frame rate was set to 45 FPS for both the ASUS and BenQ displays but the LG had to be set at 55 FPS due to limitations of the demo software.

Click to Enlarge

The ROG Swift animates at 45 FPS without any noticeable ghosting at all. The BenQ actually has a very prominent frame ghost though the image still remains sharp and in focus. The LG 34UM67 shows multiple ghost frames and causes the blade to appear smudgy and muddled a bit.

The question now is: why is this happening and does it have anything to do with G-Sync or FreeSync? NVIDIA has stated on a few occasions that there is more that goes into a VRR monitor than simply integrated vBlank extensions and have pointed to instances like this as an example as to why. Modern monitors are often tuned to a specific refresh rate – 144 Hz, 120 Hz, 60 Hz, etc. – and the power delivery to pixels is built to reduce ghosting and image defects. But in a situation where the refresh rate can literally be ANY rate, as we get with VRR displays, the LCD will very often be in these non-tuned refresh rates. NVIDIA claims its G-Sync module is tuned for each display to prevent ghosting by change the amount of voltage going to pixels at different refresh rates, allowing pixels to untwist and retwist at different rates.

It’s impossible now to know if that is the cause for the difference seen above. But with the ROG Swift and BenQ XL2730Z sharing the same 144 Hz TN panel specifications, there is obviously something different about the integration. It could be panel technology, it could be VRR technology or it could be settings in the monitor itself. We will be diving more into the issue as we spend more time with different FreeSync models.

For its part, AMD says that ghosting is an issue it is hoping to lessen on FreeSync monitors by helping partners pick the right components (Tcon, scalars, etc.) and to drive a “fast evolution” in this area.

Initial Thoughts

Our time with FreeSync has been shorter than expected and I don’t want to make any kind of concrete decisions on the technology just yet. We now have a good range of monitors in our office or on the way to help us make the best possible decision about recommendations for gamers. It took longer than we wanted to arrive, but the technology is finally available to AMD Radeon PC gamers.

When using the FreeSync display inside the VRR window, which is unique to each monitor model, the gaming experience is drastically improved over traditional VSync enabled or disabled configurations. You get a clean, tear-free and stutter-free animation and PC games look better than they ever have on an AMD GPU. The NVIDIA G-Sync experience and the AMD FreeSync experience in this case are basically identical.

Above the maximum refresh rate, AMD’s current solution is actually better than what NVIDIA offers today, giving users the option to select a VSync enabled or disabled state. G-Sync forces a VSync enabled state, something that hardcore PC gamers and competitive gamers take issue with.

Below the minimum refresh rate things get dicey. I believe that NVIDIA’s implementation of offering a variable frame rate without tearing is superior to simply enabling or disabling VSync again, as the issues with tearing and stutter not only return but are more prominent at lower frame rates. When I pressed AMD on this issue during my briefing they admitted that there were things they believed could work to make that experience better and that I should “stay tuned.” While that doesn’t help users today, AMD thinks that these problems can be solved on the driver side without a change to the AdaptiveSync specification and without the dedicated hardware that NVIDIA uses in desktop G-Sync monitors.

My time with today’s version of FreeSync definitely show it as a step in the right direction but I think it is far from perfect. It’s fair to assume that after telling me FreeSync would be sent to reviewers as far back as September of last year, AMD found that getting display technologies just right is a much more difficult undertaking than originally expected. They have gotten a lot right: no upfront module costs for monitor vendors, better monitor feature support, wide vendor support and lower prices than currently selling G-Sync options. But there is room for improvement: ghosting concerns, improving the transition experience between VRR windows and non-VRR frame rates and figuring out a way to enable tear-free and stutter-free gaming under the minimum variable refresh rate.

Even though our LG3 34UM67 has a fairly narrow VRR window at just 26 Hz, the BenQ and Acer 2560×1440 will over a much larger 104 Hz range, diminishing the impact of the negative characteristics above. I’ll be spending more time with those over the weekend and into early next week and will definitely have an updated story for our readers to follow up on.

FreeSync is doing the right things and is headed in the right direction, but it can’t claim to offer the same experience as G-Sync. Yet.