Sli Mode

Hi people,

¿UE4 Support Sli Mode?


Wouldnt that be more a matter of your graphics card and driver supporting it?
I could be wrong, but the way I remember SLI is, that it works transparent for the application…

UE4 does not support SLI

SLI requires a profile for each game to support it, it depends on what graphical features each game uses, it’s not a universal thing which is why it’s not supported with UE4 since each game that is made with the engine will have unique requirements.

Oh, then SLI has really changed… :eek:
Last time I had an SLI system running, it would simply split the rendering task based on odd/even lines, hence ScanLine Interleaving.
And no profiles were necessary…
Just out of couriosity… Why isnt it like that anymore…:confused:

It was never like that, every game that supports SLI has an SLI profile. SLI stands for Scalable Link Interface

Well, I honestly cant remember having required any sort of profile in my Voodoo2 SLI setup…
And 3Dfx claimed the acronym to be ScanLine Interleave…

The profiles are included in the Nvidia drivers. Whenever you get a new driver it’ll have info there about new SLI profiles they’ve added or what improvements they’ve made.


As I said, my SLI rig wasnt from NVIDIA :slight_smile:
I wasnt aware that NVIDIA kept the acronym, but changed its meaning and the way it works.
The closest thing to the “old way” would be SFR with a fixed ratio…
I wonder why NVIDIA didnt use the 3dfx technolgy… It delivered good results…

Things get more complex over time, my guess is that it requires some instructions on how to delegate tasks to the separate cards. It’s a similar issue that’s coming up in DirectX12 which will allow you to do something similar to SLI/Crossfire but doesn’t require the cards to be the same, in that case the game still has to be configured on how it will send tasks to the graphics cards that are available.

The way I remember it worked was that since the cards would render the frames line-wise, each card was just asked to render every other line.
The same way you can constrain rendering regions in max, POVray, etc.
Because the of the spliting on single line level, both cards received teh same amount of workload, independent from the scene to render.
And it would scale wonderfully… 4 cards, each renders every 4th line, etc…
But I guess the sheer render throughput is not the only bottleneck anymore… So no desire to max it out there…

I’ve seen the video game Tera supports SLI Mode , how they do it?
I am Spanish , so please forgive my bad English .

Tera has an Unreal Engine 3 full license–it’s not UE4
They worked with Nvidia to get SLI support.