Sign in with
Sign up | Sign in

Two Radeon R9 295X2s: A Work In Progress

Update: Radeon R9 295X2 8 GB In CrossFire: Gaming At 4K
By

Update, May 6, 2014: AMD maintains that the only supported way to hook its Radeon R9 295X2 up to a 4K monitor is through DisplayPort, and that no enthusiast will use the dual-HDMI method required for us to benchmark with our FCAT toolset. With that last point, I agree completely. DisplayPort is the only practical way to go in the real world.

But that also means leaning on Fraps exclusively for performance evaluation. We’ve already opened Pandora’s Box on that, and we know why Fraps isn’t the best solution for testing multi-GPU configurations. There’s no going back, and I just wouldn’t feel comfortable presenting Fraps data and asking you to make an exception and trust it. So, in addition to re-running all of the FCAT-generated numbers with lots of extra airflow and in two different platforms (I swapped the cards out of iBuyPower's box and into my own as a sanity check), we also ran Fraps numbers hooked up through DisplayPort. All of the results for quad-CrossFire are mentioned on the benchmark pages.

In two cases, a comparison between the results suggested an issue that went undetected in the first piece. Battlefield 4 and Grid 2 should have been much faster with four Hawaii GPUs compared to two, but weren’t. I have some guesses as to what happened, and I’ve presented them, along with all of my testing notes, to AMD’s driver team. We now report closer-to-expected frame rates in those titles.

Assassin’s Creed, Metro, Thief, and Tomb Raider come fairly close to what we saw a couple of weeks ago, and today’s re-worked charts make the same point over again. Arma 3 speeds up today versus our first evaluation of quad-CrossFire, but again, all of our testing is best-case, with maximum airflow through an open chassis.

Quantitatively, we end up with a couple of games in which AMD serves up impressive scaling given the historically difficult move from two to four GPUs. A few others demonstrate more modest scaling. And the last couple don’t scale at all, really. As a matter of principle, just based on the numbers, I stand by our original take on quad-CrossFire using two Radeon R9 295X2s: they’re a work in progress for gaming at 3840x2160. Idiosyncrasies abound, though AMD tells us that the experience from an integrator like Maingear would be significantly different.

But because some of the performance metrics suggest more attractive performance in games that we weren’t seeing before, it’s also important to consider the qualitative experience of gaming on four GPUs. In Battlefield 4, for example, the idea of 84 FPS from two 295X2s is sexy compared to one board’s 48 FPS. The stuttering you run into, however, makes the benchmark result irrelevant—you’d unplug the second card before ever trying to play that way. Assassin’s Creed IV is similarly intolerable, though AMD says that one's problematic because of Nvidia and its GameWorks library. Arma and Tomb Raider don’t escape this “Quality Index” unscathed, either. Only Grid 2 and Metro looked smooth enough to enjoy, and in the latter title, quad-CrossFire doesn’t affect performance at all.

What on earth could be to blame? First, consider the complexity of what AMD is trying to do. You have two dual-GPU boards communicating over the PCI Express bus. Each has its own PLX switch to facilitate communication on-card. However, the boards have to reach across the bus to synchronize with each other. At 3840x2160, each frame is about 33.2 MB. AMD has mechanisms in its driver to evaluate available bandwidth and cope with shortcomings by switching to software compositing. Still, ignoring one of its best practices (using a link smaller than 16 lanes or a motherboard with another PLX switch) could cause issues at 4K. But we tried isolating those variables and continued to see the same issues.

Obviously, this information is relevant to a privileged few able to consider three-grand worth of graphics hardware. But 4K is the future for a great many enthusiasts, and driving that many pixels isn’t easy. Gamers buying today are almost certainly looking at multi-GPU configurations of some sort, making twin Radeon R9 295X2s an attractive option (particularly given their outward-venting closed-loop liquid coolers). And although I continue saying good things about the 295X2, and wouldn’t have any problem using one in my personal system, there are still issues to work out with a pair operating in tandem.

Display all 69 comments.
Top Comments
  • 11 Hide
    frozentundra123456 , April 21, 2014 5:24 AM
    I am not a great fan of mantle because of the low number of games that use it and its specificity to GCN hardware, but this would have been one of the best case scenarios for testing it with BF4.

    I cant believe the reviewer just shrugged of the fact that the games obviously look cpu limited by just saying "well, we had the fastest cpu you can get" when they could have used mantle in BF4 to lessen cpu usage.
Other Comments
  • 8 Hide
    redgarl , April 21, 2014 5:17 AM
    I always said it, more than two cards takes too much resources to manage. Drivers are not there either. You are getting better results with simple Crossfire. Still, the way AMD corner Nvidia as the sole maker able to push 4k right now is amazing.
  • 2 Hide
    BigMack70 , April 21, 2014 5:24 AM
    I personally don't think we'll see a day that 3+ GPU setups become even a tiny bit economical.

    For that to happen, IMO, the time from one GPU release to the next would have to be so long that users needed more than 2x high end GPUs to handle games in the mean time.

    As it is, there's really no gaming setup that can't be reasonably managed by a pair of high end graphics cards (Crysis back in 2007 is the only example I can think of when that wasn't the case). 3 or 4 cards will always just be for people chasing crazy benchmark scores.
  • 11 Hide
    frozentundra123456 , April 21, 2014 5:24 AM
    I am not a great fan of mantle because of the low number of games that use it and its specificity to GCN hardware, but this would have been one of the best case scenarios for testing it with BF4.

    I cant believe the reviewer just shrugged of the fact that the games obviously look cpu limited by just saying "well, we had the fastest cpu you can get" when they could have used mantle in BF4 to lessen cpu usage.
  • 2 Hide
    Reynod , April 21, 2014 5:39 AM
    Great article as always Chris ... sweet and to the point without bias.
  • 2 Hide
    west7 , April 21, 2014 5:42 AM
    i wasn't expecting 295x2 in crossfire review in any time soon well done toms
  • -2 Hide
    noobsaibot99 , April 21, 2014 5:45 AM
    Nothing to do here :D 
  • -3 Hide
    noobsaibot99 , April 21, 2014 5:51 AM
    Nothing to do here :D 
  • 4 Hide
    Matthew Posey , April 21, 2014 6:07 AM
    The first non-bold paragraph says "even-thousand." Guessing that should be "eleven-thousand."
  • 0 Hide
    EricJohn2004 , April 21, 2014 6:35 AM
    Lol, I notice that too.
  • -3 Hide
    Haravikk , April 21, 2014 6:37 AM
    How does a dual dual-GPU setup even operate under Crossfire? As I understand it the two GPUs on each board are essentially operating in Crossfire already, so is there then a second Crossfire layer combining the two cards on top of that, or has AMD tweaked Crossfire to be able to manage them as four separate GPUs? Either way it seems like a nightmare to manage, and not even close to being worth the $3,000 price tag, especially when I'm not really convinced that even a single of those $1,500 cards is really worth it to begin with; drool worthy, but even if I had a ton of disposable income I couldn't picture myself ever buying one.
  • -7 Hide
    EricJohn2004 , April 21, 2014 6:38 AM
    I don't see how AMD cornered Nvidia at all. The 780Ti is still the fastest single GPU you can get, and if you put them both is crossfire/sli, they are about even. Are you talking about the fast that AMD cards have more memory than Nvidia? You can always get Nvidia cards with more memory if you want to.

    But to say one company has another one cornered is a bit bias. Not a bit, just straight up bias. I like both companys, they are both doing great IMO.
  • 3 Hide
    ddpruitt , April 21, 2014 6:55 AM
    I'm curious as to the type of loads both the CPU and RAM are seeing. I wouldn't be surprised if we're getting to the point where the bottleneck is elsewhere. I'm guessing that the GPUs are just overpowering everything else and are starving, hence the wild numbers. It also looks the driver is a beta driver, there's a lot of tuning to be done there.
  • 2 Hide
    CaptainTom , April 21, 2014 7:26 AM
    Something was definitely bottle-necking those GPUs. Oh well. Some day I think we will see all crossfire/sli combinations work the way they should...
  • -2 Hide
    CaptainTom , April 21, 2014 7:27 AM
    Something was definitely bottle-necking those GPUs. Oh well. Some day I think we will see all crossfire/sli combinations work the way they should...
  • 2 Hide
    Steveymoo , April 21, 2014 7:30 AM
    Would be interesting to see benchmarks with an 8 or 12 core xeon with workstation grade hardware. Just sayin'.
  • -5 Hide
    h2323 , April 21, 2014 7:49 AM
    You have to wonder sometimes if its the hardware/software or the people doing the testing....
  • 2 Hide
    Haravikk , April 21, 2014 8:17 AM
    Regarding the possibility of software issues; it'd be nice to see a retrospective article that looks to see if that's the case. I'd definitely be interested to know if the stability is improved after a few new driver versions to see if that's the problem, or if the hardware (or concept) is truly at fault.
  • 0 Hide
    St0rm_KILL3r , April 21, 2014 9:01 AM
    I think it's still gonna be a while when games will be made to utilize 4 gpus well at one time.
  • 0 Hide
    gsxrme , April 21, 2014 9:15 AM
    This has and will always be an issue with 3-way and 4-Way SLI or Crossfire. Nvidia and AMD both have extremely low support for this. Just spend the money on 2 cards and watercool/overclock them vs adding a 3rd or 4th card into the mix.

    After my last burn with SLI GTX295s, I will never go back to QuadSLI. I am still having an issue leaving my SLI GTX680s @ 1300MHzcore / 7Ghz Ram setup. Then again i am still at 1080p like 99% of the gamers.

    4K isn't ready until refresh rate is bumped up 60Hz- 120Hz and better HDMI standards.
  • 3 Hide
    Xavier Corraya , April 21, 2014 9:46 AM
    295x2 in crossfire?
    I think Tom went mad to catch Jerry .... :p 
Display more comments
React To This Article