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
For this article we’ve decided to do things a bit differently and lead in with a summary of our results, rather than starting with detailed results and then going to a summary. Based on past feedback most of you want to quickly know whether this works at all and how well it works, which is something we can quickly cover first before diving into individual games.
We’ll start with the graph that is of the most importance: delta percentages on a 7990, comparing Catalyst 13.6b2 to Catalyst 13.8b1 with frame pacing enabled.
The results, quite frankly, speak for themselves. In roughly half of our 6 games AMD had absolutely absurd frame pacing on Catalyst 13.6. Total War, Sleeping Dogs, and Battlefield 3 all had massive pacing issues that were the result of second frames coming far too soon after first frames, leading to a high instance of “runt” frames – that is frames that are only shown for an incredibly short period of time before being replaced with a newer frame. These are the games where micro-stuttering and/or the feeling of lower frame rates would be the most apparent.
Earlier we decided that our cutoff would be 15%-20% for an “acceptable” range for delta percentages on a multi-GPU setup, and with the exception of Total War: Shogun 2 (the only non-action game in this collection), AMD has just managed to hit that. How smooth this is going to be perceived is going to vary on a person-by-person basis, but this is right where we’d say micro-stuttering and other issues become generally unnoticeable.
For the more visually inclined, we’ve also quickly cooked up frame time graphs in FCAT showing the two 7990s. The full series is below, but we’ll print in full the Total War: Shogun 2 graph in full since it was one of the bigger problem cases for AMD’s cards without frame pacing. Shogun doesn’t have any scene transitions, but it does have some snap camera movements that leads to a clear separation between scenes. In each scene we can clearly see the much lower variability with Catalyst 13.8 with frame pacing turned on, as opposed to 13.6 with frame pacing turned off.
Similarly, turning off frame pacing results results in Catalyst 13.6-like behavior, with much higher variability compared to having frame pacing turned on.
Moving on, the next question on most readers’ minds will probably be performance. What’s the performance sacrifice for using this new frame pacing mechanism? AMD said that the performance hit should be non-existent, and strictly speaking within Catalyst 13.8 that’s true, as we get identical frame rates with it on or off. However compared to Catalyst 13.6 we are seeing a performance regression.
With the exception of Hitman: Absolution, performance is down across the board on 13.8 versus 13.6. The specific performance losses vary on the game, but we’re looking at 5-10%. However compared to the 13.5 launch drivers and again with the exception of Hitman AMD’s performance has held constant or increased. So at the very least when it comes to frame rates AMD is no worse off than they were at the launch of the 7990.
Our next summary graph is plotting the 7970GE against a pair of 7970GEs in Crossfire, to take a fresh look at AFR (Crossfire) versus a single GPU. Our editorial position has been and remains that we favor a single larger GPU over a pair of smaller GPUs when this approach is practical, and this chart demonstrates exactly why.
The delta percentages on the single 7970GE are all under 2%, versus 12%+ for the Crossfire setup. AFR simply cannot match the consistency of a single GPU at this time, which is why a high AFR is best left to being pursued after single-GPU performance has been exhausted.
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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.