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Frame Rating Dissected: Full Details on Capture-based Graphics Performance Testing

Vsync and its Effect on Frame Rating – Does it fix CrossFire?

After publishing the Frame Rating Part 3 story, I started to see quite a bit of feedback from readers and other enthusiasts with many requests for information about Vsync and how it might affect the results we are seeing here.  Vertical Sync is the fix for screen tearing, a common artifact seen in gaming (and other mediums) when the frame rendering rate doesn’t match the display’s refresh rate.  Enabling Vsync will force the rendering engine to only display and switch frames in the buffer to match the vertical refresh rate of the monitor or a divisor of it.  So a 60 Hz monitor could only display frames at 16ms (60 FPS), 33ms (30 FPS), 50ms (20 FPS), and so on with a 120 Hz monitor could also being capable of 8ms (120 FPS), etc. 

Many early readers hypothesized that simply enabling Vsync would fix the stutter and runt issues that Frame Rating was bringing to light.  To test this we looked for a game that ran right around the 60 FPS mark in our in normal testing with Vsync disabled and then set about to re-run results with it on.  We are using a standard 60 Hz monitor with the goal of being able to test some 120 Hz capability soon after we figure out a final bug or two with our capture configuration. 

First up, let’s take a look at the NVIDIA GeForce GTX 680 and GTX 680 SLI and see what shows up.

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Because the average frame rate per second graph averages out the frame times for a total of one second of time, the averages won’t quite be the straight lines you might have expected.  Looking at the GTX 680 SLI Vsync enabled results the only key item is that the frame rate doesn’t go above 60 FPS like it does with Vsync disabled.

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The single card and SLI configurations without Vsync disabled look just like they did on previous pages but the graph for GTX 680 SLI with Vsync on is very different.  Frame times are only switching back and forth between 16 ms and 33 ms, 60 and 30 instantaneous FPS due to the restrictions of Vsync.  What might not be obvious at first is that the constant shifting back and forth between these two rates (two refresh cycles with one frame, one refresh cycle with one frame) can actually cause more stuttering and animation inconsistencies than would otherwise appear.

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Based on our graph here we found that with Vsync enabled we had about 87% of our frames running at 60 FPS (16 ms) and 13% at 30 FPS (33 ms).  You might be curious how there could be 60 FPS frame rate so often with Vsync on but very few frames at 60 FPS with Vsync off, and the answer lies in the rate limiting caused by Vsync.  Because of the back pressure on the game engine caused by the longer frame times (30 FPS, 33 ms) from Vsync there is more time for the GPUs to “catch up” and render another frame at 16 ms. 

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Our ISU graph on stutter potential tells the story in a more damning light; starting at the 30th percentile the Vsync enabled setup of GTX 680s in SLI are already running at much higher frame variances and it only gets worse as we hit the 60s, 80s and 90s.  At the 90th percentile we are seeing frame variances over 12 ms, which is nearly a complete monitor refresh cycle!

 

Now let’s see how the AMD Radeon HD 7970 results change.

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Something interesting is already happening here – the Vsync enabled results from the HD 7970 CrossFire configuration are running at HIGHER average frame rates per second than with Vsync disabled!  The orange line clearly never hits the 60 FPS mark while the black line (Vsync) does. 

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Without Vsync we clearly see the runts affecting the plot of frame times here on the HD 7970s in CrossFire but enabling Vsync does appear to eliminate them! 

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With our observed frame rate we have the same results for the HD 7970 CrossFire as we did with our FRAPS results, indicating no dropped frames or runt frames.  Standard CrossFire mode still shows the horrible results we have come to expect from our analysis today.

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Our Min FPS percentile graph shows us that we are running at 60 FPS (16 ms) 85% of the time and 30 FPS (33 ms) the rest.  Because our data here is based the observed frame rates and not the FRAPS frame rates, there is no correlation between the two CrossFire runs.

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The ISU graph of stutter potential again indicates that the Vsync enabled option is introducing higher frame variances than we would like and it is doing it more dramatically and earlier than the GTX 680s in SLI. 

It does appear that enabling Vsync will help alleviate the runts issue seen with AMD Radeon cards in CrossFire but at the cost of much more frame variance and stuttered animation on games that previously didn’t exhibit that problem. 

Let's take a look at another example using CrossFire that has another particular set of circumstances.  I theorized that in a gaming scenario that bordered just under 60 FPS with a single GPU, we would still see problematic results when jumping to HD 7970s in CrossFire.  Take our Battlefield 3 2560x1440 testing: with only one HD 7970 we are running just under 60 FPS most of the time which would, with Vsync enabled, force the game to run at 30 FPS with 33ms frame times.  Ideally we would like to see that move from 33ms frame times to 16ms frame times when adding in another HD 7970 in CrossFire due to the extra performance pushing the card over 60 FPS steady.

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Our FRAPS graphs looks how we would hope and expect real-world performance to look.  While the single HD 7970 ran at a non-standard frame rate when performance was under 60 FPS, towards the end (50 sec point) where it could, we see a flat line that is partially hidden behind the pink line.  That pink line represents CrossFire HD 7970s and by doubling the number of GPUs we expected to maximize performance at 60 Hz with Vsync enabled, and we have. 

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Observed frame rates calculated by removing runts are showing the Vsync DISABLED results on the HD 7970s in CrossFire mirror what we have seen before with much lower performance.  However, the Vsync ENABLED results did not change! 

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The somewhat complicated plot diagram of frame times indicates that at no time did the frame rate of the HD 7970 cards in CrossFire go below 60 FPS or above the 16ms mark - even though there are thousands of frames under 16ms (runts) when Vsync is disabled.  Not only that but performance over the single HD 7970 with Vsync enabled is improved - rather than having jumps between the 16ms and 33ms frame times, we are locked in at 16ms - matching the 60 Hz refresh of our panel. 

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The minimum FPS percentile graphic shows the same story - the pink link representing the HD 7970s with Vsync turned on looks solid.

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Notice as well that with a static 16ms frame time we see no frame time variance at all in our ISU graph indicating that the kinds of stutter we are searching for are not showing up at all.

How is this happening?  How is enabling Vsync 'fixing' the runts and frame time issues of CrossFire?  The secret lies in the inherent back pressure of vertical sync to pace the graphics card and AMD's CrossFire engines even against its own will.  By forcing the GPUs to only render one frame every 16ms (at the maximum), Vsync is able to force the GPU to pace itself in a way that it would otherwise not.  This doesn't happen in every game though as we saw in the Crysis results first, and there is a lot more testing that needs to be done with Vsync to make a firm decision.

 

NVIDIA has a couple of different solutions in the NVIDIA Control Panel that might help: Adaptive Vsync and Smooth Vsync.  Adaptive Vsync was released with the first Kepler GPUs last year and we found it to be very effective at reducing stutter while also eliminating tearing.  Smooth Vsync is a little known feature that only exists in the driver when SLI is enabled as it takes advantage of many of the same frame metering features that SLI uses.  It attempts to keep frame rates “settled” at a level until it decides it has enough horsepower to move up to the next frame rate option for an extended period of time.  It is a very dubious description at best and NVIDIA didn’t go into much detail on how they decide if they have enough GPU overhead remaining or how long that “period of time” really is.

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I decided to run through the same Crysis 3 sequences at 1920x1080 on the GTX 680s in SLI with all four NVIDIA options enabled: Vsync off, Vsync on, Adaptive Vsync and Smooth Vsync. 

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Our FRAPS based results show the same similar looking results for standard Vsync on and off, but the adaptive and smooth Vsync options appear to be fixed at 30 FPS with the occasional hiccup on the Smooth Vsync.

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The plot of frame times is kind of confusing but the important data is to compare standard Vsync On to Adaptive and Smooth.  With the exception of the 6 or so spikes on the smooth configuration the frames are basically fixed at 33 ms, resulting in a perfectly smooth gameplay experience but at the expensive of limiting performance. 

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The observed FPS doesn’t change at all.

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Another view here shows the same thing with a fixed frame rate of 30 FPS for adaptive and smooth Vsync options.

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NVIDIA’s Adaptive Vsync shows basically 0 variance and only very minimal variance on the Smooth Vsync option at the 96th percentile.  So even though performance is lower on average, the experience is smoother.

 

NVIDIA’s additional Vsync options are definitely a strong point in favor of its technology though the Smooth Vsync only exists on SLI configurations.  I have been told that they were considering adding it to single graphics card configurations and I certainly hope they do as it adds some significant value in the same way Adaptive Vsync and Frame Rate Limiting do.

For both NVIDIA and AMD multi-GPU solutions with standard Vsync, enabling it definitely changes the story.  NVIDIA’s cards pretty much perform as we expected but for CrossFire we didn’t really know what expect with the various visual concerns.  It does appear that the runts problem was at least mostly solved with the enabling of Vsync though to be clear we are only testing a couple of game at this point – much more needs to be done. 

However, enabling Vsync creates a whole host of other potential issues that gamers have to deal with.  Even though the goal of removing visual tearing is met with the option turned on, you do add latency to the gameplay experience, as much as 60ms in some cases, from input to display.  Putting back pressure on the GPU pipeline, for both NVIDIA and AMD, means that some frames are going to be running behind schedule or behind the input timing of the game itself.  Many gamers won't want to deal with those kind of input problems and that is why many still play games with Vsync disabled.  Turning on Vsync does help AMD's CrossFire performance but it isn't the final answer just yet.

March 29, 2013 | 04:16 PM - Posted by John Doe (not verified)

Horse shit:

http://hardforum.com/showthread.php?t=1703048

March 27, 2013 | 02:36 PM - Posted by John Doe (not verified)

Moral of the story, get this before it goes out of stock:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814187196

It's a card of very limited availability and is one hell of a damn good card.

Best cooler, only Tantalum caps and no cylindrical caps over VRM area, backplated, best looking. Such a boss. Reminds me of those black 68 Mustang Bosses.

March 27, 2013 | 12:30 PM - Posted by Mountainlifter (not verified)

Great Job, Ryan and team. No, Amazing job. I've been following your frame rating articles from the first one and I've been waiting for this full reveal for a long time.

I do hope you show some frame rating benches for the GTX TITAN too (cause I own one now).

I am finding it tough not to conclude that AMD's two GPU system is completely broken although it baffles me that a company of their scale could not detect/think of such issues.

They have been known to take shortcuts on drivers before. http://forum.notebookreview.com/sager-clevo/567681-should-i-switch-out-m... (I'm only getting this from a reliable NBR forumer).

March 27, 2013 | 01:38 PM - Posted by John Doe (not verified)

AMD drivers are put out by a single guy called Catalyst Maker... he has a little team to help him out, but after all, he's just one guy.

That's why they suck.

It's been this way for AGES. The last cards that didn't in one way or another suck, were the X1950's which were made by ATi and not AMD.

Also, dual 7900 setups aren't "completely broken". That's just your pointless assumption.

If there's anything that's "completely broken", it's your wallet for shelling out $1000 for a dumbass card.

March 27, 2013 | 01:51 PM - Posted by Josh Walrath

AMD/ATI used to have a smaller driver team than NV, but actually when AMD bought ATI and started down the APU path... they hired a lot more folks to support these products.  Catalyst Maker was originaly Terry Makedon, but he has moved onto marketing more than software development.  There are (iirc) several groups now working on drivers, but their workload is arguably greater than it was before.  Supporting several different architectures spanning from GPUs to APUs is certainly no easy task, and I think they continue to hire more people.  Reviews like this provide a lot more impetus inside companies to improve their products, and the software drivers certainly are the quick fix are for AMD now.

I think that NV still has a larger driver team, and that massive server room that pretty much only works on nightly builds of drivers from NV is still much bigger than what AMD has.  However, AMD is not as far behind as many think.  But obviously from what we have seen here, and read about from other sources, their focus was not exactly where it needed to be.

March 29, 2013 | 03:12 AM - Posted by Anonymous (not verified)

That's nice and all to amd but it looks like half a decade of total screw job right now, and outright fraud.

March 27, 2013 | 10:27 PM - Posted by Mountainlifter (not verified)

just leave this website man.

March 27, 2013 | 10:29 PM - Posted by Mountainlifter (not verified)

Would you kindly... leave this website man. Thanks.

March 27, 2013 | 10:29 PM - Posted by Mountainlifter (not verified)

Would you kindly... leave this website man. Thanks.

March 27, 2013 | 10:31 PM - Posted by Mountainlifter (not verified)

Was addressing john doe, not walrath.

March 28, 2013 | 12:16 AM - Posted by Josh Walrath

Heh, you can address me.  It won't offend.  As long as I don't offend Ryan, I could be good.

March 29, 2013 | 05:43 AM - Posted by John Doe (not verified)

Hey mountainlifter, would you lift my T-Bird if it gets stuck on a mountain?

Lift my cock while you're there as well.

GG.

March 29, 2013 | 12:14 PM - Posted by Justin Anderson (not verified)

I agree John Doe is retarded and needs to leave. I think he's is trying to pick up dudes on this site he keeps telling people to suck his dick. Why don't you just go to chat roulette if you want to get your rocks off man.

March 29, 2013 | 12:14 PM - Posted by Justin Anderson (not verified)

I agree John Doe is retarded and needs to leave. I think he's is trying to pick up dudes on this site he keeps telling people to suck his dick. Why don't you just go to chat roulette if you want to get your rocks off man.

March 29, 2013 | 12:15 PM - Posted by Justin Anderson (not verified)

I agree, John Doe is retarded and needs to leave. I think he's is trying to pick up dudes on this site he keeps telling people to suck his dick. Why don't you just go to chat roulette if you want to get your rocks off man.

March 29, 2013 | 03:43 PM - Posted by John Doe (not verified)

LOL that's hilarious.

That's all.

Hahaha.

April 2, 2013 | 10:51 PM - Posted by Anonymous (not verified)

Don't tell the truth, the haterz then come forth...

I mean how many times can we give AMD the most gigantic pass ?

Not on this - this new tech with the single card to suck up the actual frames delivered to the end gamer screen with the quad SSD's to take all that in on the fly - this is called PROGRESS, and it has exposed a huge, huge amd flaw.

I feel sorry for all those foolish amd fanboys who screamed at me to buy two amd and crossfire it's a better deal and OC and blah blah blah blah - it's now a big joke.

All those "top crossfire amd gamerz" denying what was right on their screens before them - now the scientific facts show what was before them runts and ghost frames...

I haven't seen a bigger emerging scandal in the video card wars ever.

I am very interested in seeing how it plays out. Of course I will accept NO EXCUSES from amd or their fans. I never have before, but this is an even bigger mess up than even I considered AMD capable of pulling, and that is saying an aweful lot.

You just keep doing your thing and laughing at the haterz, they should be ashamed of themselves honestly.

I want to see if they went with runt and ghost frames after the 69xx series was outed as junk for crossfire by HardOcp with Terry Makedon there in the forums- AMD "became aware" according to that head Cat Maker that there "was a problem" and my guess is the solution was runts and ghosts.
That would keep the DAMAGE to the last 2 major series - but I want data all the way back to 3870/3870X2 to see how deep the rabbit hole goes.

March 27, 2013 | 01:52 PM - Posted by Anonymous (not verified)

so basically what i'm getting from this story and the one at anand is that amd has been reviewed over the years with inflated fraps #s due to more runt and drop frames that are no good to gamers?

March 27, 2013 | 02:30 PM - Posted by Noah Taylor (not verified)

You are absolutely right, AMD's setups have fraudulently inflated their benchmark numbers for years which have helped them sell products and grow their % of discrete market share. This really is the most groundbreaking reveal I've ever come across in the gaming industry.

March 27, 2013 | 02:42 PM - Posted by John Doe (not verified)

It's not like nVidia hasn't done it either:

http://tpucdn.com/reviews/NVIDIA/7950GX2/images/singlebenchlow.jpg

March 27, 2013 | 02:43 PM - Posted by Anonymous (not verified)

Yeah, I'm sure AMD's share of the discrete market has grown thanks to inflated Xfire numbers. I mean, so many people have multi-GPU setups in the first place, amirite?

Plus, jumping to the conclusion that there's deliberate "fraud" going on can only be the result of deluded fanboy thought processes. Considering FCAT is the first tool that can really show this behavior, it's rather more reasonable to believe that AMD was simply unaware of it.

March 27, 2013 | 04:04 PM - Posted by John Doe (not verified)

Alright, let me get it the easily way for you.

What the hell does the inflated CF performance figures have to do with the frame latencies? NOTHING.

The frame latency is a problem only because AMD has yet to be able to completely man up the GCN architecture.

April 3, 2013 | 11:27 PM - Posted by Anonymous (not verified)

No, fraps showed the problem, and the extended FCAT has only highlighted it even more.
The other thing that showed the problem - countless end user complaints, many times raging radeon fanboys screaming you cannot see beyond 30fps because "the human eye is incapable of it", something we call fanboy fantasy, apologetics, excuses, denial, brain washed psycho hardcore amd total verdetrol absolutist.
There are a lot of them, and that unfortunately has allowed amd to scam the entire industry for this long.

You see we still have a boatload of deniers here. Total amd fanboys, nothing will ever change their minds, no facts are facts they can accept if the facts prove amd sucks.

March 29, 2013 | 12:15 PM - Posted by Anonymous (not verified)

Yes it is, but the river in Egypt will start to grow to cover the entire earth for the amd fanboys, oh wait it already has.

BURNED in the extreme, the failure of crossfire, the scam of the decade.
Ghosts and runts, but boy oh boy our fps looks frappalicious !

LOL - so, so pathetic.

nVidia's SLI monsters ? ZERO runts, ZERO ghost frames.
PERFECTION incarnate.

Let's review:
nVidia - perfect execution, no cheating no runts, no ghost frames
amd - lying failure, HALF OF THE FRAMERATE IS A LIE. ghost runt every other frame !

ROFL amd you truly suck as bad as I have been saying for half a decade, wait no, you are worse.

Now we will get treated to endless excuses, denials, it doesn't matter, who cares, and all the rest of the radeon ragers standard operating apologetic procedures they have gang banged on the net for years.

Watch for this development: amd fanboys new spewing propaganda
" using two cards is a hassle, you should buy a single card, and just upgrade when the next best single card comes out like the 7970 with how great it is. Who wants to waste money on two cards, it's like <1% of gamers, so no one really does this at any end user level except fanatics, it's just not needed and is a budget buster. "

LOL - A thousand excuses already coming

March 27, 2013 | 03:21 PM - Posted by Wingless (not verified)

How does changing Render Frame Ahead/Pre-Rendering affect Crossfire and SLI? In Battlefield 3, people are saying it gets smoother if you change it to 0 or 1 vs the default value of 3.

Thanks for your great analysis and extremely informative video.

March 28, 2013 | 09:56 AM - Posted by Wingless (not verified)

Battlefield 3
Guide: How to Fix Low FPS - Stuttering - Lag
http://battlelog.battlefield.com/bf3/forum/threadview/2832654347723598222/

There is a well documented stuttering fix for both Nvidia and AMD users on multiple forums. I've tried this for my HD 4870 Crossfire setup and it works. This particular user from the above link has a NVIDIA GTX 470.

5.Open notepad and paste this into it and save it as "user.cfg" inside your "program files/origingames/battlefield3" folder:

RenderDevice.TripleBufferingEnable 0
RenderDevice.ForceRenderAheadLimit 1
WorldRender.SpotLightShadowmapResolution 256
WorldRender.SpotlightShadowmapEnable 0
Render.DrawFps 1

With this applied to the game, are there any differences? Render Ahead seems to really affect these results and it would be nice if it were tested with FCAT.

Thanks

March 29, 2013 | 04:40 PM - Posted by John Doe (not verified)

Do you like Winger?

They're really a crappy band but they have some decent stuff LOL.

http://www.youtube.com/watch?v=rWSVGcivuGs

March 27, 2013 | 03:43 PM - Posted by Randy (not verified)

Absolutely fantastic work Ryan. This article really blew me away and gave me a lot of tools to better understand what I've been dealing with at home. One question though: you point out that vsync can solve most of amds problems provided the frame rate doesn't have to drop from 60 to 30, in which case the drastic stutter caused by such a change adversely impacts smoothness. What if instead of using vsync you used a frame rate limit that corresponded with the apps average framerate? This way when the frame rate dips below that threshold it isn't cutting its' self in half as it would with vsync and in theory not introducing nearly as much stutter.

I advised my friend to do this with his dual 6950 setup in far cry 3 and he said it gave excellent subjective performance. I used the same method for my single 7970 and also noticed a nice bump to the smoothness of the game, but again this is all subjective. It would be awesome if you could test this as if proven correct it would give a lot of amd owners the tools to make the best of a bad situation.

Again thanks for the tremendous work you've done here, this is truly awesome work.

March 27, 2013 | 04:43 PM - Posted by grommet

Quick question- Could Lucidlogix's Virtual Vsync technology help out with the CrossFire issues?
http://www.lucidlogix.com/technology-virtual-v-sync.html
Not that this would let AMD off the hook as this needs to be taken care of in-house, but could it help?

March 27, 2013 | 05:02 PM - Posted by Anon (not verified)

That's a nice question.

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