SLI and Nvidia Surround - problems, support, future ?

General Feedback & Requests
1

Ok I can’t get either of these features to work on a standalone game build for shipping.

SLi - no matter what mode I run I can never get the second GPU to work. I haven’t tried forcing SLi because in the past that has not worked for me…

Surround - here comes the interesting part. When I play in editor viewport I can span the game on all 3 screens. When I run standalone game and set the resolution to 5760x1080 (native) the game accepts it , but does not show any image on the side monitors. BUT the second GPU seems to be kicking in (or at least it gets HOT )

SOooo can I (or Epic probably I don’t know how to ) make my game run in surround and SLi or does Nvidia have to provide a profile for it ( I have the latest drivers). My rig has 2 gtx 570 in SLI.

2

UE4 doesn’t support SLI, you may have to add that feature to your game yourself.

3

will there ever be support for sli,dula gpu’s

I got a gtx 690 then i got unreal engine 4 domos. it turned out i was getting 25-40 fps on full hd in 2 demos UE4 70-80fps, so F…k NO! NO! NO!
I wanted to create some expirienes for RIft with ue4 and now when i see that it does not suport SLI i want to smash something. so i get prformance of gtx 680 for 900$ isn’t that awesome?so now what? sell gtx 690 and get gtx 780ti ,give me a break … is there any posility that UE4 will support SLI .There should be streight and fast answer on that… couse there is a lot of people who invested in their sli configurations to get as power ful as they could and now…and now its like WTF…

is SLI coming or not going to happen, if NOT f…k all this sli thing and scream out it that is a joke

4

…will you calm down?

Also, why are there so many spaces in your post?

5

Yes calm down. It does suck it doesnt support sli, as i have GTX 680 in SLI, and boy i wish i could have SLI.

I’m not sure it ever will “out of the box”:

  1. You need to have a profile added for it (up to nvidia/people making a profile, I have expirimented with adding a profile but there are no UE4 titles to try to use similar configs of that work)
  2. With almost every iteration of Unreal Engine 4 (4.0, 4.1 , 4.2, and especially 4.3 and on because they are starting to transition to a multi-threaded renderer). The rendering engine is changing fairly drastically and sli would be broken pretty often from what i understand [new to sli scene]
6

Take a look at https://answers.unrealengine.com/questions/21746/does-the-ue4-engine-support-sli.html as to why UE4 does not support SLI out of the box. I too would like it if it were to increase performance as I have two GTX 690’s.

7

somehow the info that sombody has 2xgtx690 made me feel better lol:D

8

I understand why AFR won’t work BUT why shouldn’t Split Frame Rendering (SFR)

This analyzes the rendered image in order to split the workload 50/50 between the two GPUs. To do this, the frame is split horizontally in varying ratios depending on geometry. For example, in a scene where the top half of the frame is mostly empty sky, the dividing line will lower, balancing geometry workload between the two GPUs. This method does not scale geometry or work as well as AFR, however.

It is far from perfect but sounds more usable. Than No sli at all.

I love my SLI setup but for my next build I will go for single GPU config.

Epic just think about it maybe don’t split horizontally but vertically and ditch the scene complexity analysis to reduce the latency and I don’t see why this should’t work.

Cheers!

9

If there was a solution that works on both AMD and Nvidia, I’m sure they’d consider it.

10

why can’t the screen be cut in half? Left side for gpu nr 1 right side gpu2 with algorithm to synchronize both sides. When comes to physick maybe it could be resolved by 1 gpu for whole screen as an additional layer also synchronized with left and right layer.

Do you think that its possible that ue4 doesn’t support sli because then the sale of high end gpu’s would drop. Maybe there is some hidden agreement between companies on that. As people go crazy about Rift and ue4 is most advanced available engine to get constant 75 fps 1080p in 3d on ue4 it’s clear that gtx 780 ti is needed. There is so many games that support SLI ultra strange that ue4 does not

11

It doesn’t sound like you understand any of the technology involved.

12

This would still not resolve the problem of one GPU needing data on the other GPU. Things like post-process effects that require neighboring pixels, particles on the GPU, etc…

It’s an interesting area, however in the short term we have plenty of GPU work on the plate that will benefit folks everyone (not just folks with 2 GPU’s) - such as our parallel rendering efforts.

Cheers!

13

Snap! I never looked it from that angle. Yeah SSR will have a hard time working… even though the data in the vram in both gpu’s is the same they have no way to share with each other the thing they have calculated. Interesting…

What if one GPU handles just some calculation say everything but PP , and then sends the image to the second gpu to put the “Shiny” in.

How hard is that ?

Also will Distance Field AO in 4.3 work without SkyLights?