Direct X 12 and SLI

So i have Rise of the Tomb Raider(new dx12 patch) and GOWUltimate. SLI is not working with these games. I can't seem to figure out why. Any ideas?

Oh and I have the latest driver.

 

I'm going to assume you have the windows store version for both. If so, SLI does not work with with that version.

 

DX12 is still a work in progress give it time and patches oh and drivers

 

Last I read/heard multiGPU configurations still didn't work with Direct X 12. Best to continue using Direct X 11 and wait for Microsoft to release patches and updates to the API.

 

SLI and CrossFire both don't work with Rise of the Tomb Raider on Steam, too.

 

SLI support is up to the devs, not nVidia.

 

Yeah it seems the DX12 update for Rise Of The Tomb Raider is single GPU only, a shame as I thought it was going to be like the Ashes Of The Singularity DX12 update that required switching OFF SLI for multi GPU usage.

EDIT : Like Terepin says it's really up to the Devs.

 

It is up to the developers now. If they don't support dx12 multiadapter feature you won't see CFX or SLI.

 

The developer must implement mGPU support in DX12 as driver's ability to control the execution is greatly diminished. There is an implicit mGPU mode which works just like in DX11 but it's still has to be implemented on the app side even though this shouldn't be hard. There's also a possibility that DX12 drivers simply do not support this mode just yet.

 

This. Because of how DX12 works, SLI support (or any multi-gpu support for that matter) is up to the game developers now, not the drivers. With Rise of the Tomb Raider SLI still works with the DX11 rendering path.

 

Like rus has already explained.

Up until now SLI/Xfire was an unofficial IHV hack, it was never a part of DirectX. But with DX12 multiGPU configs are officially supported in two modes - implicit and explicit. Without going into details that you can read somewhere else, the devs will need to implement it in their games/engines.

 

Well, its a little more complicated than that
DX12 is AFR compatible, so SLI is very much possible in this API with the right driver coding and a developer patch.

 

That doesn't change the fact that without support in game SLI won't work even if drivers support it.

 

Sure, but this is no different from past DX9, DX10 and DX11 games really.

 

Multi-gpu (both homogeneous and heterogeneous modes) must be at application level. Looks like those games do not implement any multi-gpu support. Manual - application level - multi-GPU implementation can work on WStore (UWP) application too without any issues, both fullscreen/borderless and windowed mode.

I am also not sure if D3D12 will allows IHVs to deliver homogeneous multi-GPU support via driver magic (C), since the nature of the API itself is not so driver magic (C) friendly.

 

It is different. In the past a driver could enable AFR rendering with application completely unaware of this. This is impossible in DX12, the app must specifically allow for implicit multiadapter for it to work.

 

Gotta say, textures on high, SMAA, everything else maxed out, I'm very impressed with with DX12 performance at 1440p on Tomb Raider. Never saw it go under 98% GPU usage or 40FPS even in areas I would get as low as 28fps in SLI on DX11.
Sad I can't see what FPS and GPU usage SLI would give, but still.

Will MultiGPU be a big waste of time when DX12 becomes standard do you guys reckon? Or will it be easy enough to implement?

 

What I meant was, that even in DX9 the application has to be "AFR friendly" for proper multi GPU scaling to work
Even through what you are saying is theoretically correct, we will see what happens in real world scenarios.

 

Make sure to use the 0x080002F5 SLI profile in DX11 mode.
You shouldn't be seeing drops to 28fps with 2-way 980 Ti:
http://www.forum-3dcenter.org/vbulletin/showpost.php?p=10927377&postcount=2100

And we are essentially starting over with multi GPU driver and game support in DX12.
Please have a little patience and give this new API a little time to mature

 

Yah DX12 works significantly different for Multi-GPU configurations, compared to DX9/10/11.

I kinda get the feeling Multi-GPU will nearly die out with DX12 as it would be up to developers to program it directly. Up to this point it's been Nvidia and AMD/ATI who has done most of the legwork to get SLI/XFire working.

The only way I see Multi-GPU working with DX12 is if various studios get extensive help from Nvidia and AMD with programming the game engine. With Multi-GPU being such a small percentage of users (maybe ~5-6%). Either way you can tell with the quality of support for multi-GPU lately it's not that big of a concern. Nvidia and AMD both have had some big issues with Multi-GPU lately.

The only other possibly I see working is Nvidia and/or AMD releases some type of .dll Application Extension to handle AFR for DX12. I think that would be more likely over developers having to implement this on their own. That way they would pipe the rendering out to a .dll if multi-gpu configurations are detected.



Personally when Pascal gets released I'm dumping SLI it's more trouble then it's worth.