Hello,
I'm considering SLI for my next computer build, but I was told that SLI doesn't work good enough, creates microstutter and input lag and all kinds of troubles so I wasn't sure if that was a good idea. Can anyone tell me what's the current state of SLI performance quality and whether I could expect it to work great in the near future (5-6 months)?
Thanks in advance.
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From what little I know about multi-GPU configs, they do offer higher overall averages, but suffer from inconsistent frame-times (which impacts the subjective feel of the game). The conventional wisdom is that a single, more powerful, GPU is better than 2, less powerful, GPUs.
Another thing to consider is that nVidia seems to be trying to get rid of multi-GPU setups. They have already limited them to high-end cards like the 1080 and 1080 ti.
To my knowledge, Crossfire works better than SLI, and AMD seems to be trying to push to better optimize multi-GPU setups. But it would still be a better strategy to buy a single, more powerful, card, unless you were already planning on buying the fastest thing on the market...
Eh that is only a problem in the Off Topic part of the forum, you can post normally everywhere else.
#!/usr/bin/GOALKEEPERthoughts
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I will use this everywhere!
"With SLI's new HB(High Bandwidth) Bridge's and Crossfires XDMA (Crossfire Direct Memory Access)? No, there are far fewer issues than ever before. The prior limiting factor was data transfer between cards not occuring fast enough and or causing one card to wait for the other to finish rendering or transferring before displaying the finished output.
It should however be said that as of right now Crossfire X with it's XDMA systems is a much cleaner and nicer solution than even the HB SLi Bridge.
http://www.anandtech.com/show/7457/the-radeon-r9-290x-review/4
Thank you catsay, but according to this anandtech review, XDMA doesn't solve the frame times issues (causing the microstutters), only solves the bandwidth problem, which is good but not great.
Rise of the Tombraider in DX12 mode does not suffer from microstuttering at all in Crossfire.
Might be because of DX12 or AMD drivers, no clue.
Well it's a 3 year old review, it's just the one I could find for the topic right now. A lot of those problems have long since solved in the Drivers etc for crossfire on newer cards. Particularly on the Polaris architecture. SLi on the other hand is a technology that has remained almost unchanged since 2006 and even then at an architectural level it was a technology that Nvidia adopted from 3DFx's Voodoo line of cards with modern itterations having converted SLI to a PCIe based interface, with the recent HB bridge Nvidia only essentially doubled up on the bridge instead of actually solving the issue.
The HB bridge is a cheap stopgap solution honestly. It provides a bit more bandwidth at half the latency, which means almost nothing in terms of frames rendered to the screen per second... It does help the buffer parity that benefits from the lower latency.
The biggest contributions to latency are software support and GPU design. The basics of multi-GPU is that both cards do work, and one card composites and displays the work. In the last 4-5 years GPUs have become more and more capable of that second task, having plenty of hardware dedicated to compositing frames from multiple cards and displaying them on time. The issue lately has been the software interfacing that hardware. Older APIs not including the necessary features, drivers not being optimized for programs, programs not being optimized for hardware, and so on. Lots of different layers involved in getting absolute performance and they often don't always work perfectly together.
As for the CURRENT state of affairs in regards to discrete multi-GPU, it's working well. A lot of programs and applications opt to not support it at all, but the ones that do have excellent support overall and work well. I've found most games that need the extra grunt of a secondary card (Witcher III, ARMA III, Rise of the Tomb Raider) can and will use it at above 70% efficiency. Doesn't sound like much I know but it's a lot smoother than it's been.
Thank you for the information.
Do you think Crossfire works better than SLI?
AMD fixed Frame Pacing for DX9 last year was it? Or the year before? I have had a crossfire rig as my main gaming PC for many years now. It was back when the Tech Report and PCPer started doing frame time analysis (See Wasson's Inside the second) that made the problem obvious and undeniable. AMD then fixed Frame Pacing in DX11, DX9 took significantly longer. I think it needs to be stressed that the Radeon Team over at AMD took the criticism at heart though, the Frame Pacing on Crossfire has been very good ever since they fixed it. I'm am fairly sensitive to micro stutter, and I didn't really understand what the problem was until Wasson wrote his in depth article. As long as the Frame Pacing works, it is very smooth. If it doesn't work then Crossfire probably doesn't work well at all in my experience.
Has it already been five years already? Time flies. Although I have had dual Hawaii cards now for years. Had 5000-series cards before that (and has also had Nvidia, although not in SLI).
Main thing with Crossfire is that you can't expect it to always work. Last couple of years almost every major game has gotten a Crossfire profile almost at launch though, that is a noted improvement.
From Wasson's Inside the second:
"Nalasco told us there are several ideas for dealing with the jitter problem. As you probably know, vsync, or vertical refresh synchronization, prevents the GPU from flipping to a different source buffer (in order to show a new frame) while the display is being painted. Instead, frame buffer flips are delayed to happen between screen redraws. Many folks prefer to play games with vsync enabled to prevent the tearing artifacts caused by frame buffer flips during display updates. Nalasco noted that enabling vsync could "probably sometimes help" with micro-stuttering. However, we think the precise impact of vsync on jitter is tough to predict; it adds another layer of timing complexity on top of several other such layers. More intriguing is another possibility Nalasco mentioned: a "smarter" version of vsync that presumably controls frame flips with an eye toward ensuring a user perception of fluid motion. We think that approach has potential, but Nalasco was talking only of a future prospect, not a currently implemented technology. He admitted AMD can't say it has "a water-tight solution yet." "
With that being said is there any relation between G-sync and Freesync and Microstuttering?
Crossfire scales better performance wise but does still suffer from latency greater than SLI. Consider that when you're looking at those latency numbers a time of 20ms is really not enough to notice, and anything under 11ms is faster than most of the human population's reaction time when focused on their reaction (such as pushing a button on a stopwatch).
Both of these technologies were developed to solve stuttering on the output end of the pipeline, especially at higher refresh rates. So yes, they are related.
from what I understand about SLI and XF, its not really worth it. Theres benefits once in a blue moon, but very rarely do games have optimization for it or is there any actual work put in.
Owner of 2 R9 390s since launch here. If I had to do it over again, I'd just get a single Fury X and call it a day (now just waiting for Vega 10). As stated above, there are VERY few games optimized for Xfire. Off the top of my head, GTA 5 and BF3/BF4 (but not most recent BF1), are the only games that run flawlessly with Xfire on (there are a couple more I cant think of). Games like Witcher 3 get 80-100% more frames with Xfire, but become nearly unplayable due to the micro-stuttering that happens every single second while playing the game.
That sounds quite disappointing. Maybe Vega will do something about it?
I'm mostly interested in playing star citizen for now, although I'd love to play a few other games as well (Witcher 3 and Skyrim being some of them so I'd prefer it working flawlessly).
Maybe, but this time I wont be making the investment to find out the hard way lol.
I actually haven't tried SC with Xfire on in awhile. Some patches support it, some dont, but overall it worked pretty good when it was working. Im pretty sure SC will be one of those well-optimized games like GTA5 and BF4.
By "optimized" do you mean there's no microstuttering as well or just scales well in terms of performance?
Is there a list of games that work good with XFire/SLi?
Both.
Not sure about that list though, but if there was one it would probably be a bit subjective due to the fact that there are vast amounts of hardware configurations.