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Quick question re: pairing NVidia cards

Blind OwlBlind Owl Posts: 504
in Technical Help (nuts n bolts)

Thanks to information I found on these forums, I know that a pair of inexpensive 4-gig cards (e.g. 1050s) won't pool their VRAM and allow me to render large complex scenes that take more memory than either card could handle by itself.

So I made the stretch and bought an 8-gig 1080 GTX, and find I'm still facing some pretty sluggish render times even though a scene might weigh in at well under 8 gigs. This is especially true when light is bouncing off water or other reflective surfaces. Now I'm wondering if a 'helper' card (again, I'm looking at 1050s) would be a useful sidekick. I understand that the extra 4 gigs of VRAM wouldn't be used, but am I correct in assuming that the extra CUDA cores would be used? If so, it might be worth spending a few extra coins to speed things up a bit.

Comments

  • fixmypcmikefixmypcmike Posts: 19,613

    If the scene fits on the 4GB card, then the extra cores will be used.

  • Blind OwlBlind Owl Posts: 504
    edited July 2017

    Do you mean they'd only be used if the scene would fit on the smaller (4GB) card? It was my impression that, as long as it would fit on the larger card, the smaller card's CUDA cores would pitch in and speed up rendering and other tasks. Even navigating through a complex scene in iRay preview mode can be a chore.

    Dang, there goes another fine idea. Thanks for the info! yes

    Post edited by Blind Owl on
  • fastbike1fastbike1 Posts: 4,078

    @Blind Owl " sluggish render times even though a scene might weigh in at well under 8 gigs. This is especially true when light is bouncing off water or other reflective surfaces."

    You might try changing the "Max Path Length" setting. This setting controls the maximum number of light "bounces" that Iray will allow when trying to converge. The default setting is -1 which is infinete bounces. Several test have been run with settings between 7 and 11 that did not negatively affect the render. I run with 9.

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  • Blind OwlBlind Owl Posts: 504
    fastbike1 said:

    @Blind Owl " sluggish render times even though a scene might weigh in at well under 8 gigs. This is especially true when light is bouncing off water or other reflective surfaces."

    You might try changing the "Max Path Length" setting. This setting controls the maximum number of light "bounces" that Iray will allow when trying to converge. The default setting is -1 which is infinete bounces. Several test have been run with settings between 7 and 11 that did not negatively affect the render. I run with 9.

    So much to learn, and such sparse, outdated, and downright lousy (or nonexistent) documentation...

    Hey, fastbike 1, that's at least twice you've given me a promising lead on a problem that had me pulling out what's left of my hair. Cheers and thanks, eh? (as we're alleged to say in Canada wink)

  • fastbike1fastbike1 Posts: 4,078

    @Blind Owl "So much to learn, and such sparse, outdated, and downright lousy (or nonexistent) documentation..."

    True that. Sadly a lot of info from well meaning posters is hearsay, guesses, or just wrong. Plus, overall Iray behavior and perception seems to depend (greatly) on a user's hardware, their understanding of photographic or stage lighting, and their scene setups.

    Another big issue is there seems to be doubts about exactly what parts of Iray have been implemented by Daz.

    Happy to help. A number of folks on the forum have provided me with some very insightful advice and recommedations. Seems only fair to repay those efforts.

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