AMD: Southern Islands (7*** series) Speculation/ Rumour Thread

Discussion in 'Architecture and Products' started by UniversalTruth, Dec 17, 2010.

  1. ECH

    ECH
    Regular

    Joined:
    May 24, 2007
    Messages:
    682
    Likes Received:
    7
    I just read this review using the 7950 CF vs 660TI SLI. Looks like the 7950 CF won every benchmark. Then I read the conclusion :shock:.
     
  2. boxleitnerb

    Regular

    Joined:
    Aug 27, 2004
    Messages:
    407
    Likes Received:
    0
    It's nothing new that SLI is superior to CF in terms of user experience. With AFR, fps are not telling the whole story. You can read this over and over again in multiple reviews, from multiple user reports. AMD should finally work this out with CF, but I wouldn't hold my breath.
     
  3. Kaotik

    Kaotik Drunk Member
    Legend

    Joined:
    Apr 16, 2003
    Messages:
    8,131
    Likes Received:
    1,830
    Location:
    Finland
    Every bit of "extra smoothness" nVidia has increases input lag in the process
     
  4. jimbo75

    Veteran

    Joined:
    Jan 17, 2010
    Messages:
    1,211
    Likes Received:
    0
    I was under the impression that you could choose to "smooth" AFR in Nvidia's control panel but at the expense of a framerate hit?
     
  5. boxleitnerb

    Regular

    Joined:
    Aug 27, 2004
    Messages:
    407
    Likes Received:
    0
    That may be, but realistically it is not noticeable. I've been running SLI for a good 18 months now and the only thing that really adds noticeable input lag is vsync.

    @jimbo75:

    It is not known what this option does, as it is fairly new. Afaik the frame metering is done automatically in software (Fermi and earlier) and in software+hardware (Kepler).
     
  6. ECH

    ECH
    Regular

    Joined:
    May 24, 2007
    Messages:
    682
    Likes Received:
    7
    Although the review did show 7950 winning at higher frame rates nothing in the review showed AMD in a light where it needed to be at a certain frame rate. At least no specific game was pointed out causing issue. Also the 7950 is similarly priced or in some cases lower then what it was benched against. So you have 7950's offering higher frame rates and sold at a lower price point.
     
    #4066 ECH, Nov 1, 2012
    Last edited by a moderator: Nov 1, 2012
  7. jimbo75

    Veteran

    Joined:
    Jan 17, 2010
    Messages:
    1,211
    Likes Received:
    0
    Yes but [H] is sponsored by Galaxy and that supersedes everything else including reviewer impartiality.

    @ Boxleitnerb - this is a year old but good article on both, and it touches on Nvidia's sli optimisations - http://www.tomshardware.com/reviews/radeon-geforce-stutter-crossfire,2995.html

    I'm actually surprised that I didn't hear a lot more about that.

    Overall, SLI had a slight advantage with two cards, but 3-way Crossfire appeared to almost eliminate microstutter completely.
     
    #4067 jimbo75, Nov 1, 2012
    Last edited by a moderator: Nov 1, 2012
  8. boxleitnerb

    Regular

    Joined:
    Aug 27, 2004
    Messages:
    407
    Likes Received:
    0
    This article was poorly done and is very misleading. The 3-way Crossfire is clearly scaling badly which indicates a CPU bottleneck. When the cards are not fully loaded, it is completely normal that frametime consistency improves because then the CPU is the "clock generator" when it comes to releasing the frames at certain intervals, so to speak. Tom's completely failed to see this and drew the wrong conclusion. They also didn't present any more data, which I find very suspicious.

    Example:
    In Skyrim I had microstuttering with SGSSAA when my fps dropped to about 40-45. At that time the uGridsToLoad tweak that is very heavy on the CPU became popular and I tried it out. fps dropped below that previous threshold as did GPU usage, CPU load increased and the microstutter disappeared completely. I could have had the same result by adding a third (and fourth) card.
     
  9. jimbo75

    Veteran

    Joined:
    Jan 17, 2010
    Messages:
    1,211
    Likes Received:
    0
    I'm not really seeing this bad scaling in most of those benchmarks - nothing more than what I'd expect from AMD's drivers on Nvidia titles anyway (Metro and Mafia being the worst). Even then the author points out that the microstutter is best on the 3-way crossfire.

     
  10. boxleitnerb

    Regular

    Joined:
    Aug 27, 2004
    Messages:
    407
    Likes Received:
    0
    I did not talk about the review as a whole but about the section where the Tri-Fire is discussed in regards to microstutter:
    http://www.tomshardware.com/reviews/radeon-geforce-stutter-crossfire,2995-6.html

    They only show Call of Juarez where 2 GPUs provide about 140fps and 3 GPUs about 160fps. This is clearly very bad scaling, most likely due to a CPU bottleneck. No other diagrams or data are presented on this matter except this one game.

    The author confuses cause and effect. Not the reduced microstutter is the cause for reduced performance/scaling. Reduced scaling due to a CPU bottleneck is the cause for less microstutter. I have made some experiments on this by downclocking my CPU significantly which led do massively reduced microstutter in several games.
     
  11. jimbo75

    Veteran

    Joined:
    Jan 17, 2010
    Messages:
    1,211
    Likes Received:
    0
    They didn't show the stutter graphs for each game, however they have commented on them below the fps graphs.

    Metro -
    AvP -
    Call of Juarez -
    Mafia II -
    The poor scaling on the 3rd card is more likely explained as...poor scaling on the 3rd card. We've been seeing this from both companies for years. In the Tom's article the 3-way crossfire 6870's consistently score lower fps than the 580 sli (as you would expect), and consistently get noted as having lower microstutter - or it's at least 2 wins and 2 draws.
     
    #4071 jimbo75, Nov 2, 2012
    Last edited by a moderator: Nov 2, 2012
  12. sonen

    Newcomer

    Joined:
    Jul 13, 2012
    Messages:
    53
    Likes Received:
    33
    Which lag ?

    If you are talking about Frame metering and purposly introduced averaging, then 20ms-20ms-20ms will feel smoother compared to 10ms-40ms-10ms.

    If you are talking about input lag - input has nothing to do with rendering, and perceived input lag will again be more consistent in 1st case, and 2nd scenario will feel jerkier and not more responsive. Unless you magically chose to move your mouse inside that 10ms period.
     
  13. lanek

    Veteran

    Joined:
    Mar 7, 2012
    Messages:
    2,469
    Likes Received:
    315
    Location:
    Switzerland
    I dont really know if its the place for post this, but well, look like HSA gain an other valuable member and as it will surely touch future gpu acceleration.

    http://www.pgroup.com/about/news.htm#54

    (Indeed not the right place where put this... move it or delte it if needed )
     
    #4073 lanek, Nov 2, 2012
    Last edited by a moderator: Nov 2, 2012
  14. ECH

    ECH
    Regular

    Joined:
    May 24, 2007
    Messages:
    682
    Likes Received:
    7
    I've noticed that it can be induced by changing the tRAS (Active to Precharge Delay) from it's predefined value or Command Rate from 2T to 1T. So it's not just the cpu from what I've experienced.
     
  15. boxleitnerb

    Regular

    Joined:
    Aug 27, 2004
    Messages:
    407
    Likes Received:
    0

    Without tangible data, these observations are not really insightful - I don't take their word for it. They should have posted detailed frametime graphs to back up their claims.

    At least SLI is scaling very well with 3 GPUs - IF you apply proper demanding settings. If you only test with MSAA or worse, FXAA, don't expect miracles due to a CPU bottleneck at least in part of the benchmark scene. This is something that many if not all reviewers are doing wrong when benching SLI/CF.
     
  16. jimbo75

    Veteran

    Joined:
    Jan 17, 2010
    Messages:
    1,211
    Likes Received:
    0
    You're right that showing the graphs would be nice, but they'd probably be a real mess or take up far too much space. If you look at the Call of Juarez microstutter graph then imagine having another 16 cards in there they would be unreadable.

    I'm sure they do actually have the graphs for them all but they just couldn't show it in the article.
     
  17. Gipsel

    Veteran

    Joined:
    Jan 4, 2010
    Messages:
    1,620
    Likes Received:
    264
    Location:
    Hamburg, Germany
    Exactly what I thought. If something is CPU limited, the microstutter necessarily disappears (as the GPUs are waiting for the game engine, the updates are evenly distributed over time) or one has a badly programmed engine that produces also stuttering on a single GPU.
     
  18. ECH

    ECH
    Regular

    Joined:
    May 24, 2007
    Messages:
    682
    Likes Received:
    7
    Wouldn't the same apply regarding the review I posted earlier? In that review there is also no data showing any issue.
     
  19. boxleitnerb

    Regular

    Joined:
    Aug 27, 2004
    Messages:
    407
    Likes Received:
    0
    True, but [H] has always made it their task to actually play the games they benchmark (their playable setting approach). They also have a long history of testing this way and of testing SLI and CF.

    I don't trust someone who makes such basic mistakes as THG as Gipsel correctly noted.
     
  20. jimbo75

    Veteran

    Joined:
    Jan 17, 2010
    Messages:
    1,211
    Likes Received:
    0
    The game is not cpu limited though.

    [​IMG]
     
Loading...

Share This Page

  • About Us

    Beyond3D has been around for over a decade and prides itself on being the best place on the web for in-depth, technically-driven discussion and analysis of 3D graphics hardware. If you love pixels and transistors, you've come to the right place!

    Beyond3D is proudly published by GPU Tools Ltd.
Loading...