AMD Frame Pacing Explored: Catalyst 13.8 Brings Consistency to Crossfire
by Ryan Smith on August 1, 2013 2:00 PM ESTCatalyst 13.8 Results in Summary, Cont
Up next, let’s take a quick look at how the 7990 with frame pacing compares to NVIDIA’s GTX 690. NVIDIA’s frame pacing has been the gold standard thus far, so let’s see how close AMD has come to NVIDIA on their first shot.
Frankly the results aren’t flattering for AMD here, although keeping things in perspective they’re not terrible. In every last game GTX 690 has much lower frame time variability than 7990. NVIDIA has been working on this problem a lot longer than AMD has and it shows. Ultimately while it’s true this is an absolute metric when it comes to comparing results – AMD experiences more than two times the frame time variation in 5 of the 6 games – keep in mind we’re looking at the variance in frame times, rather than the frame times themselves, a first order derivative. What it means is that AMD clearly still has room for improvement, but AMD’s approximately 20% results are not a poor showing in this metric; for every individual there exists a point below which the frame time variations cease to be perceptible.
While we’re on the matter of this comparison, it’s very much worth pointing out that while AMD can’t match NVIDIA’s delta percentages at this time the same cannot be said for runt and dropped frames. Throughout our tests on Catalyst 13.8 AMD delivered 0 runt frames and dropped 0 frames. This is a massive improvement over Catalyst 13.6, which would regularly deliver runt frames and drop frames at times too. In fact even NVIDIA can’t do this well; the GTX 690 doesn’t drop any frames but does deliver a small number of runt frames (particularly towards the start of certain benchmarks). So in their very first shot AMD is already beating NVIDIA on runt frames, a concept pioneered by NVIDIA in the first place.
We’ve also posted the FCAT graphs for the 7990 versus the GTX 690 below. We can clearly see the higher variation of the 7990, while we see a few more instances of late frames on GTX 690 than we do 7990.
Moving on, we wanted to quickly compare D3D9 to D3D11 performance on the 7990. As a reminder AMD’s frame pacing mechanism isn’t enabled for D3D9, so this gives us a quick chance to look at the difference. The only title in our collection that is D3D9 capable is Total War: Shogun 2, so we’ll use that.
And there you go. Frame pacing is not available on D3D9, leading to much more variable results for the 7990 when using the D3D9 path, even though it’s otherwise faster due to the simpler effects. AMD will ultimately address D3D9 in a further phase, but in the meantime this reinforces the need for a switch to turn off Crossfire on dual-GPU cards like the 7990. NVIDIA allows this, and AMD lets you do it on multi-card setups, but with the 6990 and 7990 you are unfortunately locked into Crossfire mode at all times.
Finally, while it’s not something we can properly measure, we did want to touch upon the matter of input lag. AMD’s earlier position that frame pacing and input lag are inversely related was not wrong. At some level adding frame pacing is going to increase the input lag due to frames being held back. The question is, to what extent and is it acceptable?
The short answer is that while we can’t really give the issue the full attention it deserves without a high speed camera (something we don’t have), subjective testing is quite good. If there is a difference in input lag from enabling frame pacing, it’s not something we’re able to perceive. Despite AMD’s concerns about input lag from what usage testing we’ve done we have no problem saying that enabling frame pacing by default was the right move. In our experience there’s simply no reason not to enable it.
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waldoh - Thursday, August 1, 2013 - link
Its unfortunate it a competing company to shine light on an issue for another to address it.waldoh - Thursday, August 1, 2013 - link
took*tackle70 - Thursday, August 1, 2013 - link
I'd say it's more like expected than unfortunate. This is why competition is a good thing and why you never want one company to blow away another - competition makes all companies serve their customer better.Big time kudos to AMD for their work on this; it's nice to see real competition available again in the $500+ market.
Rezurecta - Thursday, August 1, 2013 - link
Excellent and well said.HisDivineOrder - Thursday, August 1, 2013 - link
I think he was referring to the fact that this issue was present for many years and not only did reviewers not catch on despite common complaints (and HardOCP) discussing the issue, but the company making the card was apparently completely blindsided by it after years and years of Crossfire sales. That's why people who own only one company's cards should try the other side to see that sometimes when someone says something like, "The nVidia cards are smoother in SLI than CF," sometimes--just sometimes--that's not fanboyism. Sometimes, it really is just smoother.No, I think the, "it took a competing company to shine a light on an issue," was more in reference to the fact that nVidia had to basically take AMD by the hand and slowly walk them through how to detect a problem highly prevalent on their products after years and years of waiting for them to get it.
They had to take out their own measurement software they built custom in-house and actually hand it over to the other team just to help them get it. This isn't typical competition teaching the other guy what to do.
This is like Pepsi-Cola taking Coca-Cola by the hand and saying, "Okay, so soda is supposed to have sugar and caffeine. Here is where you get it. Here is our supplier. Try it."
That's why he's saying it's sad. If AMD had figured it out on their own and fixed it, then yeah, that's competition because they FIGURED IT OUT. Instead, they didn't. It took TechReport slamming them on it with DATA after years of HardOCP just slamming them without data and thousands upon thousands of users saying, "Crossfire is not very good compared to SLI" and then nVidia hand delivering them FCAT for them to get it.
Before that, they were clueless. AMD is a company that produces discrete GPU's for the gaming market and not only did they have no clue how to test for this problem, they didn't even know there WAS a problem they were so clueless.
And that truly is very sad.
Galidou - Thursday, August 1, 2013 - link
Not sure that it was as much present in past products, I owned crossfire 6850s for a while then switched to a single 660ti to gain not much except lower temps and a little more FPS. Only game I could tell there was a real noticeable difference in smoothness was Skyrim and that was mainly because of thextures taking more than the mere 1gb my 6850s had.chizow - Friday, August 2, 2013 - link
Can't really agree with this, microstutter was documented and covered significantly in the German press for years, largely ignored by the NA press. 4870X2 microstutter problems were the first time the issue was really brought to light by PCGamesHardware, there's tons of documentation about it about if you search, here's the original test by PCGH:http://www.pcgameshardware.com/aid,653711/PCGH-pro...
Death666Angel - Saturday, August 3, 2013 - link
Multi GPU stuttering was well known about pretty much a few months into having multi GPU solutions. The issue with single GPUs also experiencing uneven frame pacing is much newer. And the believe among AMD was that it was an issue that affects AMD and nVidia equally, which is why they never thought about changing it in their drivers. Until Scott made the revelations.taltamir - Monday, August 5, 2013 - link
I personally documented single GPU multistuttering years ago (caused by lack of CPU power (C2D 8400, problem resolved going to a Q6600; using nvidia GPU), with hard data. (fraps individual frame render times record).I posted it on anandtech forums and there was a brisk discussion of it. It wasn't well known, but it shouldn't have completely blindsided the so called professionals. HisDivineOrder really said it best
chizow - Wednesday, August 7, 2013 - link
Yes I remember, there was a lot of user testing that stemmed from the initial reports on PCGH and the FRAPS frametime methodology became standard in allowing virtually any user who could download FRAPs and work a spreadsheet illustrating microstutter.I do agree though, the pros and press kept ignoring and sweeping it under the rug as if it didn't exist despite countless requests from end-users asking for more detail on it.