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Thread: GPU and SLI support - Help needed

  1. #1
    Junior Member bluepian's Avatar
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    GPU and SLI support - Help needed

    Hey guys,

    I want to buy your rendering software Bunkspeed Shot 2014 and I need a new pc system to run the software properly. Since I read a lot about requirement issues I planned to buy the following system and would be happy if you could "check" whether this system will work and let me have fun with Shot:

    Intel® Core™ i7-4770K
    16GB DDR3 RAM
    2x NVIDIA GeForce GTX780 *overclocked*, 3GB GDDR5 (SLI)
    MSI Z87-G45 (Intel® Z87 Express)

    Since I am a student I have to save some money to buy the Nvidia Quadro cards in the future... My main question now concerns the 2 Nvidia Geforce cards in SLI mode: Does Bunkspeed shot take advantage of SLI? I would expect that it does, because Shot uses Iray technology from Nvida who also creted SLI. Other option would be to buy a single Nvidia Titan. Here is the comparison from your website:

    NVIDIA GeForce GTX TITAN (6GB, 2688 CUDA cores)
    NVIDIA GeForce GTX 780 (3GB, 2305 CUDA cores)

    So what would you buy and why?

    Best regards,
    David

  2. #2
    Senior Member Aselert's Avatar
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    Hi David!

    No, forget SLI here, you don't need it in GPGPU computing, like Bunkspeed

    You're choice is very good! But my advice is to choose the graphics card with the maximum memory (Titan in this case), especially if it's for architectural renders

  3. #3
    Junior Member bluepian's Avatar
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    Thanks for your quick answer! But will SLI not work at all (so Shot will react as it would to a system with only on GTX780) or is Titan Black just a little bit better? And what about the higher CUDA cores in the SLI system? Doesn't Shot take advantage of more Cuda cores? Sorry for ansking again, but i am not too familiar with GPU issues

  4. #4
    Senior Member Aselert's Avatar
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    In fact, SLI isn't needed because it ins't for gaming here. So Shot/Pro/Drive will use every available GPU in the PC with the same speed importance, and with a near linear acceleration (1 GPU= 100%, 2 GPU = 198%, 3 GPU = 296% roughly, by example).

    Titan Black Edition is a little bit better than "simple" Titan. So if you have opportunity to buy one or two, do it!

    The more CUDA cores you, the better (in term of speed only) it is. BUT, in term of scene size, the largest memory (VRAM) you have, the better it is.
    So in this case, Titan (Classic or Black) is the best because of its 6Gb memory...

  5. #5
    Junior Member bluepian's Avatar
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    Thanks again, Aselert! So two GTX780s in SLI would be faster and have nearly the same acceleration as a titan black, but titan would offer better scene size? But why exactly is that, 2 GTX780 as well as one titan black would produce a total of 6 GB VRAM. Are multiple GPUs faster because of higher CUDA cores? Is that correct so far?

    For someone who just started to learn about these things, all these GPU issues can be quite confusing.

  6. #6
    Senior Member Aselert's Avatar
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    Lol! Ok so, to sum-up...

    1/ Please forget the "SLI" term here, really, because you don't care of it
    2/ About speed you will have (from bad to better): 780>Titan>780Ti>Titan Black (of course even a 780 isn't bad )
    3/ About scene size capacities, Titan (Black or classic) is 2 times better than 780/780Ti: 6Gb instead of 3Gb.
    4/ You can add the speed's cards, yes, but not the memory. So the smaller memory size limit the all. So 2x 780 will give you 3Gb, and 780 + Titan will give you 3Gb too... Only 2x Titan (or just 1x) will give you 6Gb.
    5/ The more CUDA cores you have, the best it is! But be careful between Kepler and Fermi cores: 1 Fermi core represent roughly 2.5/3 Kepler's cores.
    6/ I agree, at the beginning, it wasn't easy for me too to understand this operations

  7. #7
    Senior Member haknslash's Avatar
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    Quote Originally Posted by Aselert View Post
    Lol! Ok so, to sum-up...

    1/ Please forget the "SLI" term here, really, because you don't care of it
    2/ About speed you will have (from bad to better): 780>Titan>780Ti>Titan Black (of course even a 780 isn't bad )
    3/ About scene size capacities, Titan (Black or classic) is 2 times better than 780/780Ti: 6Gb instead of 3Gb.
    4/ You can add the speed's cards, yes, but not the memory. So the smaller memory size limit the all. So 2x 780 will give you 3Gb, and 780 + Titan will give you 3Gb too... Only 2x Titan (or just 1x) will give you 6Gb.
    5/ The more CUDA cores you have, the best it is! But be careful between Kepler and Fermi cores: 1 Fermi core represent roughly 2.5/3 Kepler's cores.
    6/ I agree, at the beginning, it wasn't easy for me too to understand this operations
    Couldn't of summed it up any better heh.

    And yes SLI is for gaming. Not for GPU rendering. In fact you will disable that feature in the NVidia control panel if you wish to render and then enable it if you wish to game. I only have my SLI bridge installed on work machine because....well....I like the way it looks ... but unfortunately no gaming will be done on it lol.

    If you scenes don't exceed 3 GB then there is no need for a Titan. You will get better performance on the dollar with a 780 Ti. No sense in spending big money on VRAM you'll never touch. However if you need the 6 GB then of course either Titan would be the better choice. If you want the performance of a 780 Ti and the 6 GB VRAM of a Titan then go with Titan Black as that is all it is, a combo of the two cards. Do not waste money buying the pro cards (Quadro/Tesla) as they will be dog slow for GPU rendering compared to a GeForce card.
    Last edited by haknslash; 03-24-2014 at 09:14 PM.
    Kenny Wilson
    900D ASUS Maximus VI Extreme 4770k 3x GTX 780 Ti's AX1200i 32GB RAM H100i a lot of SP120 fans
    Bunkspeed Shot Pro 2014

  8. #8
    Junior Member bluepian's Avatar
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    Thanks for bringing light into the dark, guys!

  9. #9
    Senior Member haknslash's Avatar
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    Glad we can help. It is confusing at first

    Also I'm not sure what case you're planning on using but I would recommend staying away from the aftermarket cooled cards unless they exhaust out the rear. My 780 Ti's are EVGA ACX cooled cards and they exhaust on the side. Thankfully I have a large enough case with a lot of positive pressure to keep things in check temp-wise. Still they get hot so make sure you got plenty of cooling or stick with the stock fan setup on the card. This may not be as big of an issue with 2 cards as it is with 3 or more.
    Last edited by haknslash; 03-25-2014 at 07:47 PM.
    Kenny Wilson
    900D ASUS Maximus VI Extreme 4770k 3x GTX 780 Ti's AX1200i 32GB RAM H100i a lot of SP120 fans
    Bunkspeed Shot Pro 2014

  10. #10
    Junior Member nino's Avatar
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    No SLI for Iray, but for 3dsmax

    Thanks a lot for these informations!

    In fact I thought that graphics cards could work together only in SLI mode for rendering in Iray and for real time viewport speed, but reading this thread, I understand that Iray doesn't care about SLI; so my question is about the specification of the motherboard and how to install 2 graphic cards?
    My motherboard is a Asus Z87-A. I just have to install a second GTX780 on an additional pci slot?
    Does SLI speed up max viewport?

    Thanks

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