Nvidia effectively kills 3-way and 4-way SLI for g

Nvidia effectively kills 3-way and 4-way SLI for gaming



Nvidia confirmed on Thursday that it has decided to focus mainly on 2-way SLI configurations with its new GeForce GTX 10-series of “Pascal” GPUs, and will not provide customers with a special “Enthusiast Key” to enable 3-way and 4-way SLI configurations. This downloadable key was originally planned to go live once the GTX 1080 hit the market at the end of May, but never materialized. Now we know why.

The company’s statement arrives after PC Perspective tried to benchmark four GTX 1080 cards using the 368.19 driver suite. Once the cards were installed and the drivers updated, the site went into the Nvidia’s SLI configuration panel and saw that only two of the four listed cards were enabled for SLI. Knowing that a special key to unlock the other two was on the way, the site emailed Nvidia to find out when it would be available. Nvidia responded it’d nixed the idea.

The deal here is that Nvidia doesn’t recommend setups with more than two Pascal-based cards. The company makes this stance very clear in its GTX 1080 white paper (pdf), stating that the evolution of games has made the process of providing beneficial performance scaling of more than two GPUs increasingly difficult. As an example, Nvidia says that the CPU can get bottlenecked in many games while it struggles to manage more than two graphics cards in the system.

Besides that, the GTX 1080 and GTX 1070 were built to support 2-way SLI anyway. With these chips, the company introduced a new SLI Bridge called SLI HB, capable of running the SLI interface at 650MHz, somewhat faster than the 400MHz seen in legacy SLI bridges. The new SLI subsystem also cranks out double the bandwidth between GPUs when compared to the interface used in older GeForce GPUs. Thus, all this means that gamers will see a smoother experience than prior SLI solutions.

“With the GeForce 10-series we’re investing heavily in 2-way SLI with our new High Bandwidth bridge (which doubles the SLI bandwidth for faster, smoother gaming at ultra-high resolutions and refresh rates) and Nvidia Game Ready Driver SLI profiles,” Nvidia said in an emailed statement. “To ensure the best possible gaming experience on our GeForce 10-series GPUs, we’re focusing our efforts on 2-way SLI only and will continue to include 2-way SLI profiles in our Game Ready Drivers.”

With all that said, developers still have the green light to create games utilizing two or more GPUs, and Nvidia confirmed that it would work with these developers to provide the best experience. Nvidia points out that DirectX 12 and Nvidia VR Works SLI allows developers to “directly implement and control multi-GPU support” in their games, so SLI profiles are not needed.

In Nvidia’s GTX 1080 white paper, the company explains that DirectX 12 provides new multi-GPU modes: Multi Display Adapter (MDA) mode, and Linked Display Adapter (LDA) mode. These are supported by Nvidia, and Ashes of the Singularity actually uses MDA mode, which allows the game to access each GPU individually on its own without needing the Nvidia driver to handle the load balancing. This mode utilizes any GPU installed in the system, and does not require them to be identical.

As for LDA mode, there are two versions: Implicit and Explicit. This mode requires that the GPUs be similar, and will link each GPU’s memory together to form a large “pool” for the developer. Nvidia’s SLI technology actually uses Implicit LDA mode, meaning that the algorithm control is handled by the SLI interface, while LDA Explicit and MDA modes allow the application itself to handle the algorithm control.

In other words, there’s technically hope for PC gamers who purchase and install more than two Nvidia graphics cards. But support for 3-way and 4-way configurations is now up to each game developer. Games not specifically coded to take advantage of more than two GPUs won’t see a benefit. We may see some graphically demanding games choose to support three or four video cards, but they’re sure to be the exception.

Source

Edited by DST4ME - 09 Jun 2016 at 11:44pm

Yep, db188 and I were discussing this on this thread, as well. Good to have others join the discussion of the issue at hand!

My understanding is that it's dx12 required and the 900 + series get full support, with older cards getting partial support. Not sure what partial support leaves out.

Hmmm - since AMD is still going to allow multiple cards, I wonder to what impact that may play in the market. It's probably somewhat negligible as AMD isn't really relevant at this point but it could be a definite marketing tool they use to the 'enthusiasts' provided they can provide a card that is close to NVIDIA's. Definitely an interesting decision on NVIDIA's part and the way games aren't optimized currently, I have little faith the game developers will really put a lot of resources into greater than x2 SLI.

Ohh and nice to see you DST4ME! It's been awhile!

If you spend any time over at PCPP you will see a lot of lower end custom systems going with AMD. Not with just low end GPUs. A lot of 380/390/Fury systems. Of course the NVidia crowd thinks the 380/390 are lower end units.

Frank

Good to see you DaxD

I agree highend user won't use lower end crossfire. If you don't really need GPU power any GPU will do, IMHO in that case it just comes down to the price.

AMD is not doing that great in the stock market, none of the chip makers really are other than Nvidia between intek/amd/Nvidia