We’ve been tracking NVIDIA’s G-Sync for quite a while now. The comments section on Ryan’s initial article erupted with questions, and many of those were answered in a follow-on interview with NVIDIA’s Tom Petersen. The idea was radical – do away with the traditional fixed refresh rate and only send a new frame to the display when it has just completed rendering by the GPU. There are many benefits here, but the short version is that you get the low-latency benefit of V-SYNC OFF gaming combined with the image quality (lack of tearing) that you would see if V-SYNC was ON. Despite the many benefits, there are some potential disadvantages that come from attempting to drive an LCD panel at varying periods of time, as opposed to the fixed intervals that have been the norm for over a decade.
As the first round of samples came to us for review, the current leader appeared to be the ASUS ROG Swift. A G-Sync 144 Hz display at 1440P was sure to appeal to gamers who wanted faster response than the 4K 60 Hz G-Sync alternative was capable of. Due to what seemed to be large consumer demand, it has taken some time to get these panels into the hands of consumers. As our Storage Editor, I decided it was time to upgrade my home system, placed a pre-order, and waited with anticipation of finally being able to shift from my trusty Dell 3007WFP-HC to a large panel that can handle >2x the FPS.
Fast forward to last week. My pair of ROG Swifts arrived, and some other folks I knew had also received theirs. Before I could set mine up and get some quality gaming time in, my bro FifthDread and his wife both noted a very obvious flicker on their Swifts within the first few minutes of hooking them up. They reported the flicker during game loading screens and mid-game during background content loading occurring in some RTS titles. Prior to hearing from them, the most I had seen were some conflicting and contradictory reports on various forums (not limed to the Swift, though that is the earliest panel and would therefore see the majority of early reports), but now we had something more solid to go on. That night I fired up my own Swift and immediately got to doing what I do best – trying to break things. We have reproduced the issue and intend to demonstrate it in a measurable way, mostly to put some actual data out there to go along with those trying to describe something that is borderline perceptible for mere fractions of a second.
First a bit of misnomer correction / foundation laying:
- The ‘Screen refresh rate’ option you see in Windows Display Properties is actually a carryover from the CRT days. In terms of an LCD, it is the maximum rate at which a frame is output to the display. It is not representative of the frequency at which the LCD panel itself is refreshed by the display logic.
- LCD panel pixels are periodically updated by a scan, typically from top to bottom. Newer / higher quality panels repeat this process at a rate higher than 60 Hz in order to reduce the ‘rolling shutter’ effect seen when panning scenes or windows across the screen.
- In order to engineer faster responding pixels, manufacturers must deal with the side effect of faster pixel decay between refreshes. This is a balanced by increasing the frequency of scanning out to the panel.
- The effect we are going to cover here has nothing to do with motion blur, LightBoost, backlight PWM, LightBoost combined with G-Sync (not currently a thing, even though Blur Busters has theorized on how it could work, their method would not work with how G-Sync is actually implemented today).
With all of that out of the way, let’s tackle what folks out there may be seeing on their own variable refresh rate displays. Based on our testing so far, the flicker only presented at times when a game enters a 'stalled' state. These are periods where you would see a split-second freeze in the action, like during a background level load during game play in some titles. It also appears during some game level load screens, but as those are normally static scenes, they would have gone unnoticed on fixed refresh rate panels. Since we were absolutely able to see that something was happening, we wanted to be able to catch it in the act and measure it, so we rooted around the lab and put together some gear to do so. It’s not a perfect solution by any means, but we only needed to observe differences between the smooth gaming and the ‘stalled state’ where the flicker was readily observable. Once the solder dust settled, we fired up a game that we knew could instantaneously swing from a high FPS (144) to a stalled state (0 FPS) and back again. As it turns out, EVE Online does this exact thing while taking an in-game screen shot, so we used that for our initial testing. Here’s what the brightness of a small segment of the ROG Swift does during this very event:
Measured panel section brightness over time during a 'stall' event. Click to enlarge.
The relatively small ripple to the left and right of center demonstrate the panel output at just under 144 FPS. Panel redraw is in sync with the frames coming from the GPU at this rate. The center section, however, represents what takes place when the input from the GPU suddenly drops to zero. In the above case, the game briefly stalled, then resumed a few frames at 144, then stalled again for a much longer period of time. Completely stopping the panel refresh would result in all TN pixels bleeding towards white, so G-Sync has a built-in failsafe to prevent this by forcing a redraw every ~33 msec. What you are seeing are the pixels intermittently bleeding towards white and periodically being pulled back down to the appropriate brightness by a scan. The low latency panel used in the ROG Swift does this all of the time, but it is less noticeable at 144, as you can see on the left and right edges of the graph. An additional thing that’s happening here is an apparent rise in average brightness during the event. We are still researching the cause of this on our end, but this brightness increase certainly helps to draw attention to the flicker event, making it even more perceptible to those who might have not otherwise noticed it.
Some of you might be wondering why this same effect is not seen when a game drops to 30 FPS (or even lower) during the course of normal game play. While the original G-Sync upgrade kit implementation simply waited until 33 msec had passed until forcing an additional redraw, this introduced judder from 25-30 FPS. Based on our observations and testing, it appears that NVIDIA has corrected this in the retail G-Sync panels with an algorithm that intelligently re-scans at even multiples of the input frame rate in order to keep the redraw rate relatively high, and therefore keeping flicker imperceptible – even at very low continuous frame rates.
A few final points before we go:
- This is not limited to the ROG Swift. All variable refresh panels we have tested (including 4K) see this effect to a more or less degree than reported here. Again, this only occurs when games instantaneously drop to 0 FPS, and not when those games dip into low frame rates in a continuous fashion.
- The effect is less perceptible (both visually and with recorded data) at lower maximum refresh rate settings.
- The effect is not present at fixed refresh rates (G-Sync disabled or with non G-Sync panels).
This post was primarily meant as a status update and to serve as something for G-Sync users to point to when attempting to explain the flicker they are perceiving. We will continue researching, collecting data, and coordinating with NVIDIA on this issue, and will report back once we have more to discuss.
During the research and drafting of this piece, we reached out to and worked with NVIDIA to discuss this issue. Here is their statement:
"All LCD pixel values relax after refreshing. As a result, the brightness value that is set during the LCD’s scanline update slowly relaxes until the next refresh.
This means all LCDs have some slight variation in brightness. In this case, lower frequency refreshes will appear slightly brighter than high frequency refreshes by 1 – 2%.
When games are running normally (i.e., not waiting at a load screen, nor a screen capture) - users will never see this slight variation in brightness value. In the rare cases where frame rates can plummet to very low levels, there is a very slight brightness variation (barely perceptible to the human eye), which disappears when normal operation resumes."
So there you have it. It's basically down to the physics of how an LCD panel works at varying refresh rates. While I agree that it is a rare occurrence, there are some games that present this scenario more frequently (and noticeably) than others. If you've noticed this effect in some games more than others, let us know in the comments section below.
(Editor's Note: We are continuing to work with NVIDIA on this issue and hope to find a way to alleviate the flickering with either a hardware or software change in the future.)
Subject: Displays | November 24, 2014 - 01:53 PM | Jeremy Hellstrom
Tagged: 2560x1440, mva, benq, BL3200PT, 32, professional monitor
Displays using Multi-domain Vertical Alignment, aka MVA, offer better response times than standard IPS panels and better viewing angle and colour than ones using TN, sitting somewhat in the middle of these two standards in quality and price. BenQ has released an 32", LED backlit 2560x1440 A-MVA display called the BL3200PT with a 100% colour gamut and 1.07 billion colours, aimed at the professional designer on a bit of a budget. The MSRP of $800 makes it far more affordable than many of the 4K monitors on the market and the use of MVA instead of IPS also helps lower the price without sacrificing too much quality. The connectivity options are impressive, HDMI, DisplayPort, dual-link DVI, and D-Sub, along with audio, two USB plugs and a card reader should ensure that you can connect this display to the necessary resources and it can be adjusted vertically as well as tilt and swivel and is capable of portrait mode. Check out Hardware Canucks full review here.
"BenQ's BL3200PT combines a massive screen size with an Advanced-MVA panel to create a monitor that's a perfect fit for optimizing workflow while delivering good color reproduction."
Here are some more Display articles from around the web:
- AOC U2868PQU 4K UHD 28 inch LCD Monitor Review @ NikKTech
- AOC U3477PQU 34 inch 3440x1440 IPS @ Kitguru
- ASUS RoG SWIFT PG278Q 27-inch G-SYNC Monitor Review @ Techgage
Subject: Displays | November 20, 2014 - 10:50 AM | Josh Walrath
Tagged: TN, Samsung, nvidia, monitor, ips, g-sync, freesync, amd
We have been teased for the past few months about when we would see the first implementations of AMD’s FreeSync technology, but now we finally have some concrete news about who will actually be producing these products.
Samsung has announced that they will be introducing the world’s first FreeSync enabled Ultra HD monitors. The first models to include this feature will be the updated UD590 and the new UE850. These will be introduced to the market in March of 2015. The current UD590 monitor is a 28” unit with 3845x2160 resolution with up to 1 billion colors. This looks to be one of those advanced TN panels that are selling from $500 to $900, depending on the model.
AMD had promised some hand’s on time for journalists by the end of this year, and shipping products in the first half of next year. It seems that Samsung is the first to jump on the wagon. We would imagine that others will be offering the technology. In theory this technology offers many of the same benefits of NVIDIA’s G-SYNC, but it does not require the same level of hardware. I can imagine that we will be seeing some interesting comparisons next year with shipping hardware and how Free-Sync stacks up to G-SYNC.
Joe Chan, Vice President of Samsung Electronics Southeast Asia Headquarters commented, “We are very pleased to adopt AMD FreeSync technology to our 2015 Samsung Electronics Visual Display division’s UHD monitor roadmap, which fully supports open standards. With this technology, we believe users including gamers will be able to enjoy their videos and games to be played with smoother frame display without stuttering or tearing on their monitors.”
Subject: Displays | November 19, 2014 - 07:31 PM | Sebastian Peak
Tagged: monitor, ips monitor, display, dell, 4k
Dell has released two new 4K monitors, and according to a story published by The Tech Report these are using IPS panels.
The new models are available on Dell's site priced starting at $599, which puts them into what had been TN territory just a few months ago. The original report came from TFT Central, which claimed to have leaked information about new 4K monitors from Dell with 60Hz IPS panels. Dell released the leaked model numbers at just $599 and $699 for the 24-inch and 27-inch versions, respectively.
Updated: Dell's website specifies that these are in fact IPS in the full tech specs rundown for each panel. I surmised that these could potentially be a VA or other panel type as well, as of course IPS is not the only display technology capable of wide viewing angles.
The monitors arrive factory-calibrated to 99% sRGB color (according to Dell's product pages) and feature tilt, swivel, and rotation, so they could be a great option where the full 178° viewing angle is preferred over the existing TN-based 4K offerings.
Since the introduction of the first low cost 4K TVs in the form of the SEIKI SE50UY04, and then into the wild world of MST 4K monitors from ASUS and others, and finally with the release of single stream low cost 4K panels, PC Perspective has been covering the monitor resolution revolution heavily. Just look at these reviews:
- SEIKI SE50UY04 50-in 4K 3840x2160 TV Unboxing and Preview
- SEIKI SE39UY04 39-in 4K 3840x2160 TV Unboxing and Overview
- ASUS PQ321Q 31.5-in 4K 60 Hz Tiled Monitor Review
- Samsung U28D590D 28-in 4K Single Stream 60 Hz Monitor
- ASUS PB287Q 4K UHD 28-in Monitor Review
- Acer XB280HK 28-in 4K G-Sync Monitor Review
Today we bring in another vendor's 4K consumer monitor and put it to the test, pitting against the formidable options from ASUS, Samsung, Acer and others. The Philips 288P6LJEB 4K 60 Hz monitor closely mirrors many of the specifications and qualities of other low-cost 4K panels, but with a couple of twits that help it stand out.
The Philips display is a 28-in class TN panel, has a 60 Hz refresh rate when utilizing the DisplayPort 1.2 connection option but adds connection capability that most other 4K panels in this price range leave off. Here are the specs from Philips:
Subject: Displays | November 3, 2014 - 08:36 PM | Scott Michaud
Tagged: LG, digital cinema 4k, digital cinema, adobergb, 4k
When we mention 4K monitors, they typically have a resolution of 3840x2160. Digital Cinema 4K adds an extra 256 pixels horizontally, yielding 4096x2160 (an aspect ratio between 17:9 and 19:10). LG Electronics has just released a monitor at this resolution for video and graphics professionals, and its feature set is strongly focused on that market.
First, with a Digital Cinema 4K resolution, the monitor is capable of previewing content in that resolution without scaling or cropping. Alternatively, software could preview consumer 4K ("UltraHD") and have a little leftover room for user interface elements.
What really sets this apart from other monitors is its color space features. This is an actual IPS panel, providing wide viewing angles, and it supports 10-bit color input for smoother gradients. Its color space is large, too. Beyond sRGB, it also covers 99.5% of the AdobeRGB color space and 97% of the DCI-P3 gamut. LG even has a mode that splits the monitor into two, one side in AdobeRGB and the other in sRGB. This is intended for artists and publishers to see content both in the color space of professional printers (AdobeRGB) and websites on consumer displays (sRGB).
While I believe this panel is rated at 60 Hz, it does not explicitly say that anywhere (that I found). I emailed LG for clarification and I will update if/when they reply. Update (Nov 4 @ 7:45pm EST): Still no word from LG, but one reader pointed me to an Overclockers UK product page that claims 60 Hz over DisplayPort and Mini DisplayPort. A second reader claims to own one of these monitors, which is running at 60Hz over Mini DisplayPort. It sounds like it supports 60Hz SST.
If it is a 60 Hz panel, this is an interesting, 31-inch display, especially at an MSRP of $1399.99. It undercuts competitors, like the Dell Ultrasharp 32, by over a thousand dollars. The LG 31MU97 is available now at a few online retailers.
Here they come - the G-Sync monitors are finally arriving at our doors! A little over a month ago we got to review the ASUS ROG Swift PG278Q, a 2560x1440 144 Hz monitor that was the first retail-ready display to bring NVIDIA's variable refresh technology to consumers. It was a great first option with a high refresh rate along with support for ULMB (ultra low motion blur) technology, giving users a shot at either option.
Today we are taking a look at our second G-Sync monitor that will hit streets sometime in mid-October with an identical $799 price point. The Acer XB280HK is a 28-in 4K monitor with a maximum refresh rate of 60 Hz and of course, support for NVIDIA G-Sync.
The Acer XB280HK, first announced at Computex in June, is the first 4K monitor on the market to be announced with support for variable refresh. It isn't that far behind the first low-cost 4K monitors to hit the market, period: the ASUS PB287Q and the Samsung U28D590D both shipped in May of 2014 with very similar feature sets, minus G-Sync. I discussed much of the general usability benefits (and issues) that arose when using a consumer 4K panel with Windows 8.1 in those reviews, so you'll want to be sure you read up on that in addition to the discussion of 4K + G-Sync we'll have today.
While we dive into the specifics on the Acer XB280HK monitor today, I will skip over most of the discussion about G-Sync, how it works and why we want it. In our ASUS PG278Q review I had a good, concise discussion on the technical background of NVIDIA G-Sync technology and how it improves gaming.
The idea of G-Sync is pretty easy to understand, though the implementation method can get a bit more hairy. G-Sync 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 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.
Subject: General Tech, Displays | September 22, 2014 - 11:00 PM | Scott Michaud
Tagged: esports, asus, vg248qe
I am a little torn about the term "eSports". Yes, I've used it. It is the accepted name. According to the definition, it mostly fits its role. Grammar and language are also fluid concepts, too. They can mean different things as time passes. I guess my real problem is that it attempts to snuggle up to "sports" for acceptance, but maintains a single-letter divider (unlike golf and, to some extent, curling). In my opinion, it is either a sport or it is something else entirely (a game, maybe?).
Apparently they support StarCraft, too.
Also, it should be considered legitimate. Spectator sports are for entertainment, and "eSports" are entertaining to watch. Sure, it is not for everyone -- but neither is any other sport.
Two organizations that do consider it legitimate is ASUS and Robert Morris University (RMU). The college has recently announced scholarships for the top League of Legends players. After all, a sports scholarship is just an advertisement expense from the university's view. That applies to any sports scholarship. The point is to lure students to your campus and spectators to sporting events. Consistent winnings and great players gets your name out there on both fronts. There is nothing wrong with that, as long as they uphold a high standard of education, too.
Today's news is that ASUS partnered with RMU to provide "over three dozen" monitors to the university. Specifically, the VG248QE 24-inch, 144Hz display. This is almost $10,000 USD of hardware at current retail price. The press release is unclear whether ASUS donated the panels, or if they were sold at a discount. I reached out to the university over Twitter for clarification.
Honestly, I find this interesting and an innovative extension on old practices.
Subject: General Tech, Displays | September 21, 2014 - 01:55 AM | Scott Michaud
Tagged: Oculus, VR, crescent bay, oculus connect
As they progress toward a consumer product, Oculus announced another prototype at their Oculus Connect developer conference. Dubbed Crescent Bay, the headset contains a new display, with a higher refresh rate and higher resolution, better optics, and 360-degree head tracking. It is also lighter and includes built-in speakers.
Of course, these features were not quantified with hard specifications.
Brendan Iribe, CEO of Oculus, stressed that this is not the consumer product yet. He claims that this is an increase over DK2 that is equivalent to the increase DK2 saw over the original Oculus Rift. It is not all about hardware, though. This company is engaged in hardware and software, video and audio. This should make sense considering their early acquisition of John Carmack and hundreds of other engineers. They, rightly, see themselves as a platform and, while they see game engines as necessary for VR, due to the ability to reposition the camera in milliseconds of notice, compared to film's never, they are not limiting themselves to just "games" (but yes they consider it a big part of it).
Honestly, months ago, I was sitting at my desk with its five monitors, each with bits of news posts, chats, reference material, and maybe a StarCraft tournament live stream, and Oculus was being discussed. I started to wonder if monitors, especially multiple displays, are just an approximation -- our current best effort -- of how to receive video cues from a PC. I could see a VR platform take on entertainment and even productivity with its infinite, virtual environments.
Currently, there is not even a hint about pricing and availability (as far as I found).
Subject: Graphics Cards, Displays | September 18, 2014 - 06:52 PM | Scott Michaud
Tagged: amd, freesync, DisplayPort, adaptive sync
MStar, Novatek, and Realtek, three vendors of scaler units for use in displays, have announced support for AMD's FreeSync. Specifically, for the Q1'15 line of monitors, these partners will provide scaler chips that use DisplayPort Adaptive-Sync and, when paired with a compatible AMD GPU, will support FreeSync.
The press release claims that these scalar chips will either support 1080p and 1440p monitors that are up to 144Hz, or drive 4K displays that are up to 60Hz. While this is promising, at least compared to the selection at G-Sync's launch a year earlier, it does not mean that this variety of monitors will be available -- just that internal components will be available for interested display vendors. Also, it means that there are probably interested display vendors.
AMD and partners "intend to reveal" displays via a "media review program" in Q1. This is a little later than what we expected from Richard Huddy's "next month" statements, but it is possible that "Sampling" and "Media Review Program" are two different events. Even if it is "late", this is the sort of thing that is forgivable to me (missing a few months while relying on a standards body and several, independent companies).