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Question about SLI

mmitchell_houstonmmitchell_houston Posts: 2,510
edited June 2016 in The Commons

Thinking of building a new i7 computer and setting up SLI to run dual EVGA GeForce GTX 960 Super Clocked ACX 2.0 4GB GDDR5 128 Bit Graphic Card (04G-P4-3962-KR) cards (I've got one, so I would buy another).

I understand the basics of SLI, but since most of the info out there focuses on gaming (which does not apply to me at all -- I don't play video games on my computer), I've got a few specic questions that relate to Iray.

  1. Can one card be set up to run my dual monitors and the other dedicated entirely to Iray processing?
  2. I don't want to dump the 960 card, but will two of them provide the better performance than a 970? (I think the 980s are out of my price range).
  3. Is anyone else using a similar configuration? Does the second card provide a significant boost to rendering speed?
Post edited by mmitchell_houston on

Comments

  • nicsttnicstt Posts: 11,715

    1. Yes.

    2. On paper, two cards offering more cores than one other (from the same generation) stand a chance of being better; real world experience varies.

    3. I have a 980ti for rendering, and a 970 for dual monitor display; when I add it to the rendering process, which is rare, it at best adds about 20% to the process. On paper two 970 should be about the same as a 980ti, maybe even better. The one being used to drive the monitors will obviously only offer some gain; in addition, the one used for display, if added to the rendering process, will result in a negative impact on the display.

    Do NOT use SLI.

  • DustRiderDustRider Posts: 2,880
    edited June 2016

    First, with Iray you shouldn't use/enable SLI, for gaming it's great, for rendering it's not. But the use of dual cards will improve Iray rendering speed!

    1. Can one card be set up to run my dual monitors and the other dedicated entirely to Iray processing?
      • Yes, just adjust the the advanced settings in the render settings.
    2. I don't want to dump the 960 card, but will two of them provide the better performance than a 970? (I think the 980s are out of my price range).
      • Looking at the performance figure MEC4D posted in another thread, you should get slightly better performance than a single 970. It seems the additional card does not double performance in Iray, it's more like approx. 150% , which should give you about the same as render speed as a 970 (2x SC 960's may be a bit faster than a stock 970)​
    3. Is anyone else using a similar configuration? Does the second card provide a significant boost to rendering speed?
      • I can't answer this specifically. See #2 above.

     

    Post edited by DustRider on
  • mmitchell_houstonmmitchell_houston Posts: 2,510
    DustRider said:

    First, with Iray you shouldn't use/enable SLI, for gaming it's great, for rendering it's not. But the use of dual cards will improve Iray rendering speed!

    1. Can one card be set up to run my dual monitors and the other dedicated entirely to Iray processing?
      • Yes, just adjust the the advanced settings in the render settings.
    2. I don't want to dump the 960 card, but will two of them provide the better performance than a 970? (I think the 980s are out of my price range).
      • Looking at the performance figure MEC4D posted in another thread, you should get slightly better performance than a single 970. It seems the additional card does not double performance in Iray, it's more like approx. 150% , which should give you about the same as render speed as a 970 (2x SC 960's may be a bit faster than a stock 970)​
    3. Is anyone else using a similar configuration? Does the second card provide a significant boost to rendering speed?
      • I can't answer this specifically. See #2 above.

     

    So, you're saying to run two cards without SLI? Hmmm. Don't really know much about that option.

  • evilded777evilded777 Posts: 2,482
    mmitchell_houston said:
    DustRider said:

    First, with Iray you shouldn't use/enable SLI, for gaming it's great, for rendering it's not. But the use of dual cards will improve Iray rendering speed!

    1. Can one card be set up to run my dual monitors and the other dedicated entirely to Iray processing?
      • Yes, just adjust the the advanced settings in the render settings.
    2. I don't want to dump the 960 card, but will two of them provide the better performance than a 970? (I think the 980s are out of my price range).
      • Looking at the performance figure MEC4D posted in another thread, you should get slightly better performance than a single 970. It seems the additional card does not double performance in Iray, it's more like approx. 150% , which should give you about the same as render speed as a 970 (2x SC 960's may be a bit faster than a stock 970)​
    3. Is anyone else using a similar configuration? Does the second card provide a significant boost to rendering speed?
      • I can't answer this specifically. See #2 above.

     

    So, you're saying to run two cards without SLI? Hmmm. Don't really know much about that option.

    It easier than an SLI Config, really... just plug them both in, plug the monitors into one and set Studio to use the other for rendering. Shouldn't really need anything special.

  • evilded777evilded777 Posts: 2,482
    edited June 2016
    evilded777 said:
    mmitchell_houston said:
    DustRider said:

    First, with Iray you shouldn't use/enable SLI, for gaming it's great, for rendering it's not. But the use of dual cards will improve Iray rendering speed!

    1. Can one card be set up to run my dual monitors and the other dedicated entirely to Iray processing?
      • Yes, just adjust the the advanced settings in the render settings.
    2. I don't want to dump the 960 card, but will two of them provide the better performance than a 970? (I think the 980s are out of my price range).
      • Looking at the performance figure MEC4D posted in another thread, you should get slightly better performance than a single 970. It seems the additional card does not double performance in Iray, it's more like approx. 150% , which should give you about the same as render speed as a 970 (2x SC 960's may be a bit faster than a stock 970)​
    3. Is anyone else using a similar configuration? Does the second card provide a significant boost to rendering speed?
      • I can't answer this specifically. See #2 above.

     

    So, you're saying to run two cards without SLI? Hmmm. Don't really know much about that option.

    It easier than an SLI Config, really... just plug them both in, plug the monitors into one and set Studio to use the other for rendering. Shouldn't really need anything special. But I could be wrong.

    quoted when I meant to edit.

    Damn insomnia

    Post edited by evilded777 on
  • MEC4DMEC4D Posts: 5,249

     Iray will see only 1 card with your connect the cards with SLI bridge , you will need  to  disable it under Nvidia Panel if you want any boost with second card .

    sometimes second card will give additional 50% boost cutting the rendering time in half for example

    1 card : 8 min

    2 cards: 4 min

    3 cards : 2 min

    that is the latest GPU scaling with the latest DS build , sometimes 2 cards will give you 176% speed it all depends of what you render and your system specifications like CPU and RAM speed as it will affect the speed as well even if you use only GPU for rendering , also using separate card for monitor will speed up the rendering time of your 2 cards and using less VRAM

    The utilization of the GPU depends also of your rendering setting , with base rendering setting the utilization is sometimes only 80% per GP , with architectural or caustic samplers set on always 100% , so more complex scenes will use full power house .

    The nvidia iray viewport worked for me best with 6000 cuda cores anything more and it will slow down , how more cards you add how less CPU power you get as it have to work for all cards so you can see longer delay or that reason you need to increase the msec speed under Draw Mode tab , viewport utilize CPU as well as rendering even if rendered only with GPU since CPU need to update your viewport changes and sent it to the cards , and while rendering it need to write it down to your temporary files , in short good balance between GPU and CPU with fast RAM is important , with bunch of Cuda cores and slow CPU you will get nothing what you would expect since iray need them both for best performance .

    Last month I made 3 different types of rigs for iray so I am talking from my own experiences 

    970 cards are good and cheap the only negative side here are less VRAM and more power usage, but having a lot of 970 in your system will give you 25% more horse power than buying high end cards for the same price , also rendering will use less power than gaming and between 60-70% only 

    mmitchell_houston said:
    DustRider said:

     

    So, you're saying to run two cards without SLI? Hmmm. Don't really know much about that option.

     

  • mmitchell_houstonmmitchell_houston Posts: 2,510
    MEC4D said:

     Iray will see only 1 card with your connect the cards with SLI bridge , you will need  to  disable it under Nvidia Panel if you want any boost with second card .

    sometimes second card will give additional 50% boost cutting the rendering time in half for example

    1 card : 8 min

    2 cards: 4 min

    3 cards : 2 min

    that is the latest GPU scaling with the latest DS build , sometimes 2 cards will give you 176% speed it all depends of what you render and your system specifications like CPU and RAM speed as it will affect the speed as well even if you use only GPU for rendering , also using separate card for monitor will speed up the rendering time of your 2 cards and using less VRAM

    . . . 

    970 cards are good and cheap the only negative side here are less VRAM and more power usage, but having a lot of 970 in your system will give you 25% more horse power than buying high end cards for the same price , also rendering will use less power than gaming and between 60-70% only.

    Thank you very much for the information. I have decided that it's time for a new build, and you've definitely given me something to think about.

  • mmitchell_houstonmmitchell_houston Posts: 2,510

    In these scenarios, do the cards need to be the same?

    Could a 960 run the monitors and a 970 handle rendering?

    Or, for that matter, a 960 run the monitors, and a 960 and a 970 be assigned to rendering?

     

  • kaotkblisskaotkbliss Posts: 2,914
    mmitchell_houston said:

    In these scenarios, do the cards need to be the same?

    Could a 960 run the monitors and a 970 handle rendering?

    Or, for that matter, a 960 run the monitors, and a 960 and a 970 be assigned to rendering?

     

    Yep

  • MEC4DMEC4D Posts: 5,249

    if you have 2 960 then use for rendering and 970 for monitor

    if only 960 and 970 then 960 for monitor and 970 for rendering

    if you mix the faster card with a slower card for rendering then you lose performance on the faster card  if both are selected for rendering ..  the GPU scaling working best if the card are from the same series 

    mmitchell_houston said:

    In these scenarios, do the cards need to be the same?

    Could a 960 run the monitors and a 970 handle rendering?

    Or, for that matter, a 960 run the monitors, and a 960 and a 970 be assigned to rendering?

     

     

  • mmitchell_houstonmmitchell_houston Posts: 2,510
    MEC4D said:

    if you have 2 960 then use for rendering and 970 for monitor

    if only 960 and 970 then 960 for monitor and 970 for rendering

    if you mix the faster card with a slower card for rendering then you lose performance on the faster card  if both are selected for rendering ..  the GPU scaling working best if the card are from the same series 

    Thanks. I'll keep that in mind!
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