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

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  • Reply 21 of 83
    xsmixsmi Posts: 137member
    Quote:
    Originally Posted by onlooker


    Also, just so you know. Those are not listed as 5100 XEONS. I don't think they are woodcrests.



    Thanks for setting the reccord straight. Did Intel release another dual core Xeon? These are the systems Phil referenced in the keynote yesterday.
  • Reply 22 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by xsmi


    Thanks for setting the reccord straight. Did Intel release another dual core Xeon? These are the systems Phil referenced in the keynote yesterday.







    From the dreaded wiki I hate so much.



    Dual-Core Xeon

    Paxville DP



    Dual-Core Xeon LV

    Sossaman as the Dual-Core Xeon LV



    Dual-Core Xeon (65 nm NetBurst)

    Dual-Core Xeon codenamed Dempsey. This is the 5000 series in your dell based on netburst. I think it's 80% slower than woodcrest according to intel



    Dual-Core Xeon (65 nm Intel Core Microarchitecture)

    Dual-Core Xeon codenamed Woodcrest, the first Intel Core Microarchitecture workstation version of the Intel Core 2 processor. This is the Apple Mac Pro workstation Processor. This would be the 5100 series
  • Reply 23 of 83
    Quote:
    Originally Posted by onlooker


    It's not a software issue it's a hardware issue. The only real software issue would be that possibly Apple didn't releasing the SLI driver because they want the poor comparisons to true 16X SLI machines.

    Sure you can SLI two 16x cards, but you reduce both cards by half. because there is only one 16x lane. Being that SLI usually just renders every other frame (odd on one, even on the other) per card you can only go as fast as your slowest connected lane. Which would be your 8X lane. It's freggin pointless to use two 16x cards at 8X each when you can use one 16X card at 16X.



    So it is a hardware issue.



    It's not a hardware issue. With the right drivers, SLI will run on a Mac. Nvidia won't code them for OS X. And, to set the record straight, each card renders half of the screen, not alternating frames.
  • Reply 24 of 83
    onlookeronlooker Posts: 5,252member
    Quote:

    Nvidia won't code them for OS X.



    Apple hasn't coded them for OS X. Nvidia has nothing to do with it. But it is still a hardware issue. No matter how you look at it you can't get dual 16X out of one, 8x, and one 16x lane.

    Quote:

    And, to set the record straight, each card renders half of the screen, not alternating frames.



    I'm pretty sure your thinking of Dual Link DVI outputs for the 30" display not SLI because AFR is far more popular, and SFR is rarely used.



    But SLi does have two modes.



    - AFR (Alternate Frame Rendering)

    - SFR (Split Frame Rendering)



    - AFR is the more widley used, and better solution.
  • Reply 25 of 83
    Quote:
    Originally Posted by onlooker


    Apple hasn't coded them for OS X. Nvidia has nothing to do with it. But it is still a hardware issue. No matter how you look at it you can't get dual 16X out of one, 8x, and one 16x lane.



    Yeah, but you can get 2 8x lanes, which is all you need. Look at the nForce4 SLI. And Nvidia has to sign off on the drivers. They simply won't let them run on an Intel chipset. I see that changing soon.



    Quote:

    I'm pretty sure your thinking of Dual Link DVI outputs for the 30" display not SLI because AFR is far more popular, and SFR is rarely used.



    But SLi does have two modes.



    - AFR (Alternate Frame Rendering)

    - SFR (Split Frame Rendering)



    - AFR is the more widley used, and better solution.



    I was thinking of SFR, as that must have been how they did it when SLI first came out. My mistake.
  • Reply 26 of 83
    screedscreed Posts: 1,077member
    Quote:
    Originally Posted by theapplegenius


    It's not a hardware issue. With the right drivers, SLI will run on a Mac. Nvidia won't code them for OS X. And, to set the record straight, each card renders half of the screen, not alternating frames.



    It is a hardware issue, in part. On the PC side, the two cards are connected with an SLI bridge.
  • Reply 27 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by theapplegenius


    Yeah, but you can get 2 8x lanes, which is all you need. Look at the nForce4 SLI. And Nvidia has to sign off on the drivers. They simply won't let them run on an Intel chipset. I see that changing soon.



    First part.



    The two 8x lanes isn't really any faster than one 16x lane. It's a waste.



    Second part.

    They already did.



    Nvidia already released a Nforce dual 16X lane SLI board for Conroe. Apparently there is a bus issue, or something with woodcrests that engineers had not figured the best possible solution for at the time. That is what someone in here said, so that is second hand info. I don't know why, and I'm not going to dig through the technology papers right now to figure out how to make it work so I'm going with that explanation for now, but I personally think Nvidia, and intel should already be past the figuring stage, and spec-ing out a final design. Their engineers are top notch, and they should be able to work it out. If it has something to do with intels chipset you can bet they are already in talks so they both can make modifications on their future designs so they work. I would have to think so anyway.
  • Reply 28 of 83
    Quote:
    Originally Posted by sCreeD


    It is a hardware issue, in part. On the PC side, the two cards are connected with an SLI bridge.



    Not needed. Especially with the 7300GT.

    Quote:
    Originally Posted by onlooker


    First part.



    The two 8x lanes isn't really any faster than one 16x lane. It's a waste.



    Then why does it matter if Apple only has a 16x and an 8x slot if neither can actually be saturated?



    Quote:

    Second part.

    They already did.



    Nvidia already released a Nforce dual 16X lane SLI board for Conroe. Apparently there is a bus issue, or something with woodcrests that engineers had not figured the best possible solution for at the time. That is what someone in here said, so that is second hand info. I don't know why, and I'm not going to dig through the technology papers right now to figure out how to make it work so I'm going with that explanation for now, but I personally think Nvidia, and intel should already be past the figuring stage, and spec-ing out a final design. Their engineers are top notch, and they should be able to work it out. If it has something to do with intels chipset you can bet they are already in talks so they both can make modifications on their future designs so they work. I would have to think so anyway.



    It's because they can't get the HT -> Bus chip to operate at 333MHz. The nForce for Intel is a terrible chipset anyway, and the *only* thing they need to do is write drivers. In fact, I could run SLI on a 975x chipset with hacked nVidia ForceWare drivers.
  • Reply 29 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by theapplegenius




    Then why does it matter if Apple only has a 16x and an 8x slot if neither can actually be saturated?





    It's because they can't get the HT -> Bus chip to operate at 333MHz. The nForce for Intel is a terrible chipset anyway, and the *only* thing they need to do is write drivers. In fact, I could run SLI on a 975x chipset with hacked nVidia ForceWare drivers.



    First part: Please elaborate on that first part, or rephrase it. It leaves too much room for guesswork.



    Second:

    You can not have full speed SLI on a 975x chipset. The 975X chipset has two physical x16 slots that are split up at the North-bridge from one single 16X lane into two bogus x16 slots with x8 bandwidth each. It's a ruse. Look it up. Those 16X slots are a fallacy FYI. This is the same results you'll get if Apple provided the driver accept I don't think they split their 16X lane. Your trying to say it can happen on the PowerMac, or the Mac Pro if they gave you the driver, but I personally don't think Apple wants the comparisons to true full speed dual 16X SLI computers made against their PowerMac, or their new Mac Pro, which is why I think Apple is not providing the SLI driver until dual 16X is available. So it's still a hardware issue. This comparison would provide to much bogus ammunition against their new union with intel. (Much of that part is just an opinion. It is only a theory of my own. I have no idea what, or why Apple does what they do, but it is a bit of sound reasoning that makes total sense to me)



    Sure you could use that dual 8X SLI PC waste but why? It's pointless when you can run one 16X card at full speed, and get the same results. But it's not pointless if you had two full speed 16X lanes running 2 cards at full speed like true full speed 16X SLI has.
  • Reply 30 of 83
    Quote:
    Originally Posted by onlooker


    First part: Please elaborate on that first part, or rephrase it. It leaves too much room for guesswork.



    The difference (with a 7800GTX, the fastest card at the time) beteen SLI on 2 x8 slots and 2 x16 slots was within the margin of error, telling me that no card, not even the 7800GTX, saturates the x8 slot.



    Quote:

    Second:

    You can not have full speed SLI on a 975x chipset. The 975X chipset has two physical x16 slots that are split up at the North-bridge from one single 16X lane into two bogus x16 slots with x8 bandwidth each. It's a ruse. Look it up. Those 16X slots are a fallacy FYI. This is the same results you'll get if Apple provided the driver accept I don't think they split their 16X lane. Your trying to say it can happen on the PowerMac, or the Mac Pro if they gave you the driver, but I personally don't think Apple wants the comparisons to true full speed dual 16X SLI computers made against their PowerMac, or their new Mac Pro, which is why I think Apple is not providing the SLI driver until dual 16X is available. So it's still a hardware issue. This comparison would provide to much bogus ammunition against their new union with intel. (Much of that part is just an opinion. It is only a theory of my own. I have no idea what, or why Apple does what they do, but it is a bit of sound reasoning that makes total sense to me)



    Sure you could use that dual 8X SLI PC waste but why? It's pointless when you can run one 16X card at full speed, and get the same results. But it's not pointless if you had two full speed 16X lanes running 2 cards at full speed like true full speed 16X SLI has.



    If you run CrossFire on the 975x, it splits the top slot into 2 x8 slots. No performance decrease from that. Dual x16 is a marketing ploy until cards actually come out that can fully saturate the x16 bus, and Apple actually uses one, which will be a fair bit longer. And SLI will always beat one card, 2 x16 slots or not. Just because the bandwidth is there doesn't mean it's being used.
  • Reply 31 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by theapplegenius


    The difference (with a 7800GTX, the fastest card at the time) beteen SLI on 2 x8 slots and 2 x16 slots was within the margin of error, telling me that no card, not even the 7800GTX, saturates the x8 slot.



    Quote:
    Originally Posted by theapplegenius


    If you run CrossFire on the 975x, it splits the top slot into 2 x8 slots. No performance decrease from that. Dual x16 is a marketing ploy until cards actually come out that can fully saturate the x16 bus, and Apple actually uses one, which will be a fair bit longer. And SLI will always beat one card, 2 x16 slots or not. Just because the bandwidth is there doesn't mean it's being used.



    Ok, you pretty much said the same thing twice so I don't need to agree twice, but in the first part GeForce 7950GX2 is currently the fastest consumer level performance card from Nvidia so do we actually know if there isn't a card made that isn't saturating the 8x slot yet? This single cards has dual GPU's, and from many quick google searches I think it does.



    Point two. Just how long is graphics technology going to remain not saturating that slot? (I think less than a year 8x slots will be a well known graphics bottle neck) I think there are a few cards that do need 16X now including the GeForce 7950GX2.

    Graphics, and GPU speed, and technology over the past 5 years has been growing at a faster pace than CPU speed, and technology. Nvidia, and ATI have not yet gone dual core, and soon will, although I'll bet you money ATI will be very shortly shortly now that AMD acquired them, and we will see those 16X slots be utilized by both within a year.



    I, like Many people, expect to get 5 years of use at least out of their computer. I upgrade anyway, but I still think dual 16X lanes is where this is all headed because of growth of graphics speed, and technology, and if Apple isn't using it once it's technically available I'd be very surprised.



    And that about sums up what's on my mind.
  • Reply 32 of 83
    Quote:
    Originally Posted by onlooker


    Ok, you pretty much said the same thing twice so I don't need to agree twice, but in the first part GeForce 7950GX2 is currently the fastest consumer level performance card from Nvidia so do we actually know if there isn't a card made that isn't saturating the 8x slot yet? This single cards has dual GPU's, and from many quick google searches I think it does.



    Agreed, My mistake. Techinically, it's 2 GPUs, and so it requires an x16 slot. Though running Quad-SLI seems to be a problem.

    Quote:

    Point two. Just how long is graphics technology going to remain not saturating that slot? (I think less than a year 8x slots will be a well known graphics bottle neck) I think there are a few cards that do need 16X now including the GeForce 7950GX2.

    Graphics, and GPU speed, and technology over the past 5 years has been growing at a faster pace than CPU speed, and technology. Nvidia, and ATI have not yet gone dual core, and soon will, although I'll bet you money ATI will be very shortly shortly now that AMD acquired them, and we will see those 16X slots be utilized by both within a year.



    I wholeheartedly agree, but as I said earlier (I think I said it, at least), Apple never gets these parts, and when they do, it's old hat on the PC side, so I don't see why we need to wait on dual x16 slots. The 7300GT is in no way, shape, or form saturating the x8 bus.



    Quote:

    I, like Many people, expect to get 5 years of use at least out of their computer. I upgrade anyway, but I still think dual 16X lanes is where this is all headed because of growth of graphics speed, and technology, and if Apple isn't using it once it's technically available I'd be very surprised.



    And that about sums up what's on my mind.



    And how many people upgrade graphics cards in their Power Macs? 1 percent? 2 mabye?
  • Reply 33 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by theapplegenius






    And how many people upgrade graphics cards in their Power Macs? 1 percent? 2 mabye?



    I do. When they get old. I have older macs in various places in my house, and I have upgraded, and updated all of them. Graphics, hard drives, and memory are always a necessary. Processors usually come last - they seem to cost the most, and by the time I need to do that I usually just box the Mac up, and buy a new one, and the others make a room change.
  • Reply 34 of 83
    Quote:
    Originally Posted by theapplegenius


    And how many people upgrade graphics cards in their Power Macs? 1 percent? 2 mabye?





    Considering how many few people on here, which is (let's be honest) two stops short of geek central, to it, I'd be surprised if it were that much.
  • Reply 35 of 83
    Quote:
    Originally Posted by onlooker


    I do. When they get old. I have older macs in various places in my house, and I have upgraded, and updated all of them. Graphics, hard drives, and memory are always a necessary. Processors usually come last - they seem to cost the most, and by the time I need to do that I usually just box the Mac up, and buy a new one, and the others make a room change.



    Okay, that's one.



    Buehler... Buehler...
  • Reply 36 of 83
    onlookeronlooker Posts: 5,252member
    Quote:
    Originally Posted by theapplegenius


    Okay, that's one.



    Buehler... Buehler...



    There are more besides me, there are sites dedicated to hardware hacking PC graphics cards to work in Macs, and I neglected to mention our Windows PC counterparts that have been eyeballing the Mac since bootcamps introduction. I don't, and wont have our crossover users year over year #'s, but PC users have a greater tendency to upgrade than Mac users do.
  • Reply 37 of 83
    mr. hmr. h Posts: 4,822member
    Some further information regarding the pointlessness of SLI in a Mac Pro (unless I've mis-understood something):



    According to this, the Mac Pro doesn't have any 8x PCI-E slots. The Graphics card goes in a 16x slot, slots 2 and 3 are 4x slots, and slot 4 is a 1x slot.
  • Reply 38 of 83
    xsmixsmi Posts: 137member
    Quote:
    Originally Posted by Mr. H


    Some further information regarding the pointlessness of SLI in a Mac Pro (unless I've mis-understood something):



    According to this, the Mac Pro doesn't have any 8x PCI-E slots. The Graphics card goes in a 16x slot, slots 2 and 3 are 4x slots, and slot 4 is a 1x slot.



    That's bummer. Does it seem as if some corners were cut developing this machine?
  • Reply 39 of 83
    tubgirltubgirl Posts: 177member
  • Reply 40 of 83
    mr. hmr. h Posts: 4,822member
    Quote:
    Originally Posted by tubgirl


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



    up to 3 slots with 8 lanes each.



    Ah... Good stuff, thanks
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