What You Need to Know About NVIDIA Iray

March 9, 2016 2 comments

What You Need to Know About Iray

If you haven’t figured it out already, I’m a big fan of using Iray for rendering with Daz Studio 4.8+. While spending time cracking out on it, I’ve figured out a few things I thought were important and worth sharing. I think they’re especially good to know if you’re considering buying a new GPU.

With that being said, I’m just going to dive right in…

    • If you’re tweaking a scene, rendering then canceling, rendering then canceling, eventually your VRAM will get full and Iray will stop using your GPU for rendering and switch to your CPU. Which typically equals longer rendering times. It can even happen when letting the render finish completely, though, for whatever reason, it seems to manage the VRAM better in this second scenario.
    • The solution, when it switches over to your CPU, you have to close Daz Studio and restart it. Then everything will be back to normal again. Also, if you keep the number of render preview windows open at a time to a minimum, when your Render Target is New Window, it seems to help the VRAM from getting as full.
    • I have verified that this is a known issue with the Daz Development Team.
    • When it first happened to me I thought one of my GPUs went out. When Iray switches from GPU to CPU I can hear it, because the fans on my water cooler crank up. I then fired up my GPU monitoring software and saw one of the cards wasn’t being used. Long story short, I finally realized the only reason the other card was running was to run my monitor, my GPUs were fine, then I contacted DAZ…
    • When using Iray with multiple GPUs, all the data being processed for rendering has to fit into each card’s VRAM independently. Which means if you have a 4GB card and a 6GB card, and the scene to be rendered requires over 4GB VRAM, the 4GB card will be excluded.
    • I’ve verified this with folks from both Daz and NVIDIA.
    • If your NVIDIA card doesn’t have at least 4GB VRAM, Daz Studio will default to CPU rendering.
    • I also confirmed this with Daz. (After the public release of Daz Studio 4.9.)


Well, I hope you learned something! If you found this post valuable, don’t forget it to share it with someone else.

Catch you on the flipside…



2 Responses to “What You Need to Know About NVIDIA Iray”

  1. Pack says:

    Hi Landon!
    I am a new user in IRay, do you know where find tutorials for beginners and advanced users for Iray?
    By the way Iray is te faster/quality render engine that I have tested (compared to Mental Ray, VRay, Arnold)

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