Dual video cards on Mac Pros. Does this mean they support SLI?

135

Comments

  • Reply 41 of 83
    tubgirltubgirl Posts: 177member
    you can only use the 16 lanes from the north bridge for slot 1 and 2 though, i dont know how big performance hit you'll take running the other gfx cards through the south bridge...?
  • Reply 42 of 83
    onlookeronlooker Posts: 5,252member
    One thing that I suggested Apple could do a few weeks ago with SLI that Apple has done is being able to configure your bandwidth. You can take bandwidth from one 4x slot, and use it in the other 4x slot giving you an 8x slot. Somebody shot me down when I said it saying it was an engineering nightmare, or something, but look what has happened. I LOVE IT!



    I hate to toot my own horn, but I'm going to. Everything, all the way back the name Mac Pro (My Pro Mac idea) has been precisely what I predicted Apple would do. Other than actually create the Pro Mac itself, but at least the name is there. Almost.
    • All Woodcrest lineup. No one even thought they would use this processor but me. I had to argue the point that conroe was a consumer processor for weeks, and that Woodcrest was for workstations. I also said they would use the old Xeon's Replacement way before that.

    • 3GHZ in the top model - Everybody said it would be way too expensive.

    • Mac Pro / Pro Mac - This prediction pre dates the Mac Book Pro by about 2 months.

    • Configurable PCI-E slots.

    • Hot swappable drive bay chassis. / This isn't there, but my point was to be able to exchange them quickly, and that we got it.

    • More HD's - Nobody thinks that we need this kind of space any more, and we should be using external enclosures. Sure Beyond 3 TB's you do, but this is a perfect start for video.



      Anyway. I think I personally had the best track record in predicting this machine this year, and I just wanted to get some recognition. Even if it was by me.



    [EDIT} Although the one thing that I thought was shocking was the Choices for video cards. I expected to see better nvidia cards like the 7900 , and 7800. I don't think they would go all the way down to 7300 as their only option for regular consumer card. I'm guessing their Nvidia supplier hit the sweet spot on a price point for that one. Although that is just a guess. The ATI card is a good card. I looked it up. I'm starting to wonder if a person can run that in dual 8x in crossfire on a Mac?
  • Reply 43 of 83
    xsmixsmi Posts: 137member
    Quote:
    Originally Posted by tubgirl


    http://developer.apple.com/documenta...inkElementID_3



    up to 3 slots with 8 lanes each.



    I saw that too but I think Apple will wait for true x16. Just a hunch.



    BTW, I havn't had the chance to check but how much faster is x8 SLI than x16 single? Onlooker you kind of aluded to it being about eual. Is that correct?

    Also is crossfire ATI's SLI?
  • Reply 44 of 83
    iposteriposter Posts: 1,560member
    From what I understand, at this point in time SLI/Crossfire give an imperceptible to the human eye increase in performance, sometimes even a decrease, for double your money.



    Quote:

    SLI doesn't always give a performance benefit - in some extreme cases, it can lower the framerate due to the particulars of an application's coding. This is also true for ATI's Crossfire, as the problem is inherent in multi-GPU systems. -Tom's Hardware



    So remind me again, unless you're a pro gamer who wants 2 FPS more than the next guy, what is the importance of it?



  • Reply 45 of 83
    Quote:
    Originally Posted by iPoster


    From what I understand, at this point in time SLI/Crossfire give an imperceptible to the human eye increase in performance, sometimes even a decrease, for double your money.







    So remind me again, unless you're a pro gamer who wants 2 FPS more than the next guy, what is the importance of it?







    It's a big difference when gaming at resolutions over 1600x1200. Otherwise it's a big fat waste.
  • Reply 46 of 83
    tubgirltubgirl Posts: 177member
    remeber folks, 8 lanes is a lot of bandwidth and the 7300 will run 'all out' on a 8x port and just fine on a 4x slot too.

    if youre looking at nvidias dual-gpu monster cards then 8 lanes won't cut it.

    but that card isnt even in the deck, is it?...
  • Reply 47 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by xsmi




    BTW, I havn't had the chance to check but how much faster is x8 SLI than x16 single? Onlooker you kind of aluded to it being about eual. Is that correct?

    Also is crossfire ATI's SLI?





    Yes Crossfire is ATI's version of SLI, and I'm waiting for ATI to offer up an answer to see if one can use crossfire on a Mac Pro.



    X8 SLI vs. 16x single tests are still out. The only card that it seems can over saturate the 8X Slot, and actually needs a 16X slot that I am aware of is a Nvidia's 7950GX2.



    So the test we would be specifically looking for is a NVIDIA GeForce 7900 GTX in SLI mode vs. the single 7950GX2. But if you look at the specs of the GX2 Nvidia didn't actually replicate 2x 7900's. They toned down the clock speed on both GPU's, and some other features, but I still think it's going to be the closest test available if anyone does it.



    I can't find a specific test, or tests that compares this information on similar enough machines to make it an accurate enough comparison. CPU speed, and the # of CPU's of the machines testing are always too far apart for me to get an accurate idea. And in testing the 7950GX2 in SLI there were too many issues.



    The question on 16X SLI vs. 8X SLI will be answered shortly because Nvidia finally released the driver for using the 7950GX2 in an SLI setup today. (08/09/06) None of the beta drives tested that I saw benchmarks on were ready for prime time, and I had searched all over last week. I went through at least 15 sites that said there was serious problems with the Quad SLI driver. So we should soon be able to see an accurate comparison pop up in the usual places within a few days, or however long it takes for them to do benchmark articles.
  • Reply 48 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by tubgirl


    remeber folks, 8 lanes is a lot of bandwidth and the 7300 will run 'all out' on a 8x port and just fine on a 4x slot too.

    if youre looking at nvidias dual-gpu monster cards then 8 lanes won't cut it.

    but that card isnt even in the deck, is it?...





    That depends. There are a few sites that used to hardware hack PC cards to work in PPC Macs. If that is even needed now I don't know, but I'm sure someone from one of those sites is going to try, and throw a 7950GX2 in a Mac Pro fairly shortly. If not. Someone like toms hardware will probably try it anyway. Everybody is going to want to benchmark the new Mac Pro. So hold your horses I think there's a storm comin'.
  • Reply 49 of 83
    I don't think you can crossfire a Mac Pro, because if memory serves (and it may not), the slot next to the x16 slot can only run at 4x or 1x
  • Reply 50 of 83
    onlookeronlooker Posts: 5,252member
    Because the Mac Pro has Configurable PCI Express Bandwidth the 1, and 2 slots can be either 16X, and 8X, or 8X, and 8X. or a number of configurations as you can see here.
  • Reply 51 of 83
    right you are - I knew about the option changing, I somehow mentally switched the 2nd and 3rd slots when I was writing that. My bad.
  • Reply 52 of 83
    come to think of it - they gave slot 2 the same power capabilities they gave the graphics slot, and reduced power to the other two slots. But how many watts do CFed x1900xts take?
  • Reply 53 of 83
    onlookeronlooker Posts: 5,252member
    Come on Zach look it up. I've been digging up most the info in this thread. I'm tired.
  • Reply 54 of 83
    Just to throw out an interesting tidbit that hasn't been mentioned here from what I have read.



    AMD is buying ATI.

    http://www.appleinsider.com/article.php?id=1907

    http://www.gizmodo.com/gadgets/hardw...azy-189382.php



    In case you guys didn't know Intel's "on board" graphics system (in systems like the Mac Book) is built by ATI.



    There were some claiming that Intel was killing the use of ATI on there systems because of the merger, but it doesn't appear to be true, for now.

    http://www.dailytech.com/article.aspx?newsid=3494



    But there are still rumblings around Intel and ATI even if the current licensing deal isn't dead between Intel and ATI.

    http://www.neowin.net/index.php?act=view&id=34297



    This could get interesting for those of us that do very high end graphics work.



    Also, it's known to many a developer that NVIDIA cards (when doing GPU level work) are much easier to create code for than ATI cards. You have to play some tricks to get ATI cards to work properly when doing some specific graphics routines on a Mac.
  • Reply 55 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by iPoster


    From what I understand, at this point in time SLI/Crossfire give an imperceptible to the human eye increase in performance, sometimes even a decrease, for double your money.







    So remind me again, unless you're a pro gamer who wants 2 FPS more than the next guy, what is the importance of it?









    2-FPS. LOL Who fed you that line? SLI can give up to a 70% increase in performance in some games. So if you were getting 100FPS you could conceivably get 170FPS.



    Not only that - If your happy with your FPS, which you'll never be, you can increase your resolution, and enhance your image quality, and texture settings.



    The Geforce 7950GX2 (SLI on a single card) is the only card that will allow you to play Oblivian using HDRI texture maps at high screen resolutions.



    Although you are right that in some cases you actually see a decrease in performance if your game is entirely CPU bound like Half Life 2 that will be the case, but you can easily turn SLI off, and on at any time on the fly.
  • Reply 56 of 83
    kim kap solkim kap sol Posts: 2,987member
    Will there ever be multiple-core GPUs? I remember a debate on this very forum in which some people were claiming that GPUs already have multiple cores (i.e. more vertex-shaders, etc....claiming that adding more vertex-shaders increases the number of cores is as nonsensical as saying that more ALUs = more cores)...



    But I'm talking about two 'full' chips on one here...the true meaning of 'dual-core'...does it still make sense to have SLI anymore? Are the PCIe 16x channels already saturated? SLI is as old as 3Dfx Voodoo 2's.



    The two-cards-on-one thing seems like the lazy way of fitting two GPUs into a single slot.
  • Reply 57 of 83
    Quote:
    Originally Posted by onlooker


    Come on Zach look it up. I've been digging up most the info in this thread. I'm tired.



    Yo - onlooker, I thought you were the hard-core gamer dude here. Anyhow - there's enough power. Slots 1 and 2 can take up the same amount of power each.
  • Reply 58 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by ZachPruckowski


    Yo - onlooker, I thought you were the hard-core gamer dude here. Anyhow - there's enough power. Slots 1 and 2 can take up the same amount of power each.



    Actually I'm not a big gamer, although you could say I do some heavy lifting using 3D applications. But in all seriousness I have been a fan of this technology since it's reintroduction by Nvidia. I think it's an asset to the platform. If the Mac had a large gamer population switch to our platform it would bring us all good things. More Mac software, games, etc. etc. etc,
  • Reply 59 of 83
    Wassup guys? My first post here. I sometimes look at some apple forums to take a look at what the zealots are up to now. This time a spotted an SLI thread and I have to say that this really takes teh cake. I personally have a working SLI in my computers and it pains to see when people who don't know much about it talk like they know everything. \ So let me clear up some konfusion.



    1)
    Quote:

    2-FPS. LOL Who fed you that line? SLI can give up to a 70% increase in performance in some games. So if you were getting 100FPS you could conceivably get 170FPS.



    Not only that - If your happy with your FPS, which you'll never be, you can increase your resolution, and enhance your image quality, and texture settings.



    The Geforce 7950GX2 (SLI on a single card) is the only card that will allow you to play Oblivian using HDRI texture maps at high screen resolutions.



    Although you are right that in some cases you actually see a decrease in performance if your game is entirely CPU bound like Half Life 2 that will be the case, but you can easily turn SLI off, and on at any time on the fly.



    No! You cannot turn SLI on or off on the fly. Every time you enable or disable SLI it requires a reboot.



    2) My eyes bleed everytime somebody mentions ATI SLI so let me put this straight. ATI has Crossfire and Nvidia has SLI.



    3)
    Quote:

    ... blah blah full 16x & 16x PCI-e SLI has double performance versus 8x & 8x configurations...



    Again, False. Many tests have shown that there is virtually no difference in the 6000- or 7000-series when using full or 8x PCI-e. When enablin SLI-AA and using 512mb 7900GTX, 7800GTX or 7950GTX is the only time when it makes a difference. Even then it is not major.



    4)
    Quote:

    ... blah blah SLI bridge is not required/useful anymore...



    Wrong! SLI bridge is required on the high power cards or otherwise there will not be enough bandwith to tranfers data between the cards and not using the bridge effectively destroys everything gained by using SLI. Just like buying a Ferrari without weels. SLI does work without the bridge on the weaker cards such as the 7300GT, because they are so slow that they do not require the extra bandwith, but the bridge is still recommend. On a side note, my personal opinion is that the SLI bidge looks hella cool.



    5) It is my view (and some others as well) that SLI or Crossfire will NEVER be seen on an Apple computer (At least on this decade). There are many reasons to this and some of them are here:



    a) (Certified) SLI requires an Nvidia nForce chipset to work well (look at current nForce 5 and 4 on AMD) and the previous SLI-on-intel chipsets have been total bull. ATI Xpress chipsets on AMD have been good only since the latest addition of the 3200-series. Now that ATI is under AMD's wing (Intel's biggest rival), Intel will absolutely NOT allow ATI to buy a licence to use their chipsets on intel boards. Apple tends to rely on robust workstation/server chipsets from intel and so it has little or no interest on using an enthusiast/gaming/overclocking chipset on its flagship machine.



    b) Apple has been wanting to avoid the "gaming machine" -tag to look serious in the eyes of creative professional (Apple's biggest customer segment) and getting SLI/Crossfire really does not help.



    c) The Mac Pro (only machine that SLI or Crossfire will fit in) has a very small market share and even less of the Mac Pro buyers use their machine for gaming. Also, ATI and Nvidia have to do a little redesign to all the cards they want to use on the apple platform, which is a major burden compared to the number of actual cards sold and market share. Because of this, Nvidia and ATi have no interest in porting multi-gpu technology over to Mac os X. It took Nvidia 4 years to get SLI working on windows and now you think that they should spend more time on getting SLi into a dying market? I mean come on!? They have massive projects going on like the upcoming 8000-series, all the Vista hassle, Quad SLI drivers, normal driver updates etc.. and you think they should spend time getting SLI and new cards onto a platform, whichs has ½% market share, no "real" gamers, no new games, worse-than-xp 3D performance (compare WoW on Mac Os X vs. XP)?



    d) Im afraid that these two comics represent the Apple (gaming) platform quite accurately



    Clicky



    Clicky vol. II



    If you wanna see some real gaming machines, I suggest you head over to http://www.xtremesystems.org/forums/. Take a look in the water cooled case galleries etc I recommend it



    6) If Apple actually gets SLI or Crossfire, I post a public apology here.



    I rest my case. Have a nice day.
  • Reply 60 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by Somalimafia


    Wassup guys? My first post here. I sometimes look at some apple forums to take a look at what the zealots are up to now. This time a spotted an SLI thread and I have to say that this really takes teh cake. I personally have a working SLI in my computers and it pains to see when people who don't know much about it talk like they know everything. \ So let me clear up some konfusion.



    I think your adding more confusion. #1 I too have a working SLI system.



    Quote:
    Originally Posted by Somalimafia


    1) No! You cannot turn SLI on or off on the fly. Every time you enable or disable SLI it requires a reboot.



    Obviously "on the Fly" was a bad choice of terminology here on my part - my bad, but you are correct..

    Quote:
    Originally Posted by Somalimafia


    2) My eyes bleed everytime somebody mentions ATI SLI so let me put this straight. ATI has Crossfire and Nvidia has SLI.



    Who said ATI had SLI? The question that was posed was is Crossfire ATI's version of SLI. To that the answer given was "yes" because Crossfire is obviously ATI's answer to SLI.



    Quote:
    Originally Posted by Somalimafia


    3) Again, False. Many tests have shown that there is virtually no difference in the 6000- or 7000-series when using full or 8x PCI-e. When enablin SLI-AA and using 512mb 7900GTX, 7800GTX or 7950GTX is the only time when it makes a difference. Even then it is not major.



    You should read the thread before you start posting. We already went through this, and your telling us nothing new, and it seems more like you got that last bit of info from reading us than anything.



    Quote:
    Originally Posted by Somalimafia


    4) Wrong! SLI bridge is required on the high power cards or otherwise there will not be enough bandwith to tranfers data between the cards and not using the bridge effectively destroys everything gained by using SLI. Just like buying a Ferrari without weels. SLI does work without the bridge on the weaker cards such as the 7300GT, because they are so slow that they do not require the extra bandwith, but the bridge is still recommend. On a side note, my personal opinion is that the SLI bidge looks hella cool.



    I missed that part. Unless someone was talking about the 7950GX2 where you don't need the bridge.



    Quote:
    Originally Posted by Somalimafia


    5) It is my view (and some others as well) that SLI or Crossfire will NEVER be seen on an Apple computer (At least on this decade). There are many reasons to this and some of them are here:



    Ohh Boy here we go. And we were the know it all's. Apparently we are ready for a schooling on "What Apple thinks" now.



    Quote:
    Originally Posted by Somalimafia


    a) (Certified) SLI requires an Nvidia nForce chipset to work well (look at current nForce 5 and 4 on AMD) and the previous SLI-on-intel chipsets have been total bull. ATI Xpress chipsets on AMD have been good only since the latest addition of the 3200-series. Now that ATI is under AMD's wing (Intel's biggest rival), Intel will absolutely NOT allow ATI to buy a licence to use their chipsets on intel boards. Apple tends to rely on robust workstation/server chipsets from intel and so it has little or no interest on using an enthusiast/gaming/overclocking chipset on its flagship machine.



    Did that actually add up to anything? I'm not sure.



    Quote:
    Originally Posted by Somalimafia


    b) Apple has been wanting to avoid the "gaming machine" -tag to look serious in the eyes of creative professional (Apple's biggest customer segment) and getting SLI/Crossfire really does not help.



    I tend to avoid proclaiming "I know what Apple thinks" posts because chances are you don't.



    Quote:
    Originally Posted by Somalimafia


    c) The Mac Pro (only machine that SLI or Crossfire will fit in) has a very small market share and even less of the Mac Pro buyers use their machine for gaming. Also, ATI and Nvidia have to do a little redesign to all the cards they want to use on the apple platform, which is a major burden compared to the number of actual cards sold and market share. Because of this, Nvidia and ATi have no interest in porting multi-gpu technology over to Mac os X. It took Nvidia 4 years to get SLI working on windows and now you think that they should spend more time on getting SLi into a dying market? I mean come on!? They have massive projects going on like the upcoming 8000-series, all the Vista hassle, Quad SLI drivers, normal driver updates etc.. and you think they should spend time getting SLI and new cards onto a platform, whichs has ½% market share, no "real" gamers, no new games, worse-than-xp 3D performance (compare WoW on Mac Os X vs. XP)?



    Nvidia doesn't port anything to the Mac. Nvidia gives Apple source code. It's never ported by Nvidia.

    ATI does however, and there is no real evidence AMD will stop any current projects they were working on. Apple uncharacteristically chose the ATI card as their high-end consumer card for a reason. Personally I think the reason was that SLI wasn't possible on that machine. I know little about crossfire, but to me from the pictures of it that I've seen it looks as it's likely that it could work now.



    Quote:
    Originally Posted by Somalimafia


    d) Im afraid that these two comics represent the Apple (gaming) platform quite accurately



    Clicky



    Clicky vol. II



    If you wanna see some real gaming machines, I suggest you head over to http://www.xtremesystems.org/forums/. Take a look in the water cooled case galleries etc I recommend it



    I didn't bother reading the comics because chances are there is just one more person pretending they know what Apple thinks writing it, and those people annoy me weather it be Mac user or PC.



    Quote:
    Originally Posted by Somalimafia


    6) If Apple actually gets SLI or Crossfire, I post a public apology here.



    I rest my case. Have a nice day.



    Then maybe we'll see you soon. Maybe we wont.

    Ether way welcome to the forum and BTW, why do you come to Mac forums anyway?
Sign In or Register to comment.