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raytracing in UE4 /Vray + Single/Multi GPU setup in UE4

Hi,
I ‘ve two questions and is why my title is laboriously long;)

  1. With Raytracing in UE4 v4.22 is investment in Vray for UE4 justifiable now? Are equal results possible with just UE4?
  2. im wondering if the way things stand I would be better off with a single gpu setup with an RTX 2080 ti 11Gig or 2 x RTX 2080s 16Gig for raytracing in UE4?
    I know there is dev coming for multi gpu setups but interested if Id get better performance from a single or two cards.
    thanks for any shared experiences, help or advice

I’m not sure what you mean by the first question, if you wish there’s the option to render things with Vray from within UE4, but that’s just more for convenience. The real-time raytracing is not going to be quite as good as a Vray render, but it will be much much faster and a lot of people are OK with the slight quality/accuracy decrease for such a big improvement in speed.
UE4 can’t take advantage of multiple GPU’s so that won’t help in UE4.
Vray does have multi-GPU support, for RTX cards you need NVLink for that, but I don’t know that Vray for UE4 supports that or if it’s just their main versions like Vray for 3ds Max.

@DanH71

1- You can just start just with UE4.22 and decide later about Vray for UE4. UE4 will always aim for games first when introducing technology, but each effort made is always thinking on archviz and film, with these last two increasing investments quite a lot.
2- I think you will want to start with one card, because the support for multi-GPU is not present yet, you can get your stuff done right now. When the support for multi-GPU become available, any combination of 2 cards will offer more than a single card, being more memory and more cuda cores a great deal. If you are into archviz or film, I would go straight to 1 x 2080TI. Once the support for multi-GPU comes out you can have even 2 x 2080TI. If you going for just gamedev, 1 x 2080 will be more than enough, even for experimenting a bit of film for your games, with the option to add another one later when multi-GPU comes out.

Just a point as far as multi-GPU goes, Nvidia has a technology called NVLink which is like an SLI bridge which requires two of the same cards (that support NVlink) to work.
DirectX 12 has a feature that supports combining multiple GPU’s of any type.
So it depends on what kind of multi-GPU feature would get integrated in terms of what hardware you need. Ultimately, I wouldn’t get your hopes up, DX12 has been available for a while and Epic so far hasn’t indicated that they plan to support multi-GPU.

Actually at GDC 2019 Epic showed in their slides that multi-GPU support will happen, but didn’t state any release for it to come out.

PS: Check the video at the time pointed out 45:25 : https://youtube.com/watch?v=gYf33FSxK2s

PS2: reconfirmed in theGDC 2019 Postshow | Unreal Engine Livestream at March 28th 2019

Hi Nilson and thanks to you and the others for your input. Yes, saw GDC19 and was what I was referring to. Like you say multi gpu will happen it’s just a matter of when and whether having more than 1 will have a negative impact on the engines running. I can live with both cards not being utilised but have read a post or two elsewhere that people have had display and other anomalies occur when running two cards. I will think long and hard but as you say maybe 1 ti will be a good start. It’s not so much for gaming but automotive configurators, stills and perhaps cinematics.

As for VRay within unreal I will probably wait and like you suggest see what UE4s implementation has to offer and become acquainted with that and if I feel it lacking can always try the Vray trial for a bit.

will keep checking Google for multi gpu user experiences using unreal 4.22.

Thanks again
Dan

@DanH71 while multi-GPU is not implemented you can expect several issues when people try do use them with UE4, definitely you should avoid. Raytracing is a feature that will take some time to be fine tuned along with other recent engine changes and they will only touch multi-GPU when those are in place and stable, or it would be another variable to make things hard to diagnose and fix.

@NilsonLima yeh, that makes perfect sense.

Now just got to find the money for a workstation with a rtx 2080 ti in it and the surrounding parts to do it justice!:wink: