Opinion: Is the multi-GPU option now over?

AMD has been shooting CrossFire for some time, while NVIDIA has now announced the end of SLI.

The multi-GPU line has undergone quite a transformation with the introduction of the new explicit APIs, as in the case of DirectX 12 and Vulkan, the application already ensures the proper use of resources. With this, the old solutions, i.e. the AMD CrossFire and NVIDIA SLI options, got a serious stomach.

AMD announced last summer that the new Radeon RX 5000 series would no longer support traditional CrossFire, while NVIDIA announced next to the new driver released yesterday that SLI’s GeForce-based GeForce reason, and from the beginning of next year, new SLI profiles will no longer be issued for older cards, regardless of whether the particular game could support the technology or not.


While the decisions may seem cruel, they were actually made to the company in question for good reason. Multi-GPU technologies designed for traditional, obsolete APIs have been working less and less well, making it completely unnecessary to maintain them. However, the new generation of consoles will practically execute DirectX 11, so more effectively, more serious games will work on any PC via an explicit API anyway, and there is no CrossFire or SLI within them.

However, the above does not mean the end of multi-GPU options at all. AMD and NVIDIA have shut down technologies that are not already working, and if they are kept artificially alive, there will be no benefit from them either. In contrast, both DirectX 12 and the Vulkan API have explicit multi-GPU features and are accompanied by a standard WDDM 2 AFR option. So if a game runs on a DirectX 12 or Vulkan API and supports multiple GPU modes for one of the explicit APIs, it will of course scale to two or more VGAs depending on how that program handles them. So the concept remains, and due to the nature of its operation, manufacturers no longer have to deal with it, they only need to support WDDM 2 AFR from the drive side, and this requires a minimum of two DMAs within the hardware, which is required by the DirectX 12 API anyway. asynchronous DMA capability.

Thanks to the above, the new drivers are extremely simple in terms of multiple GPUs, as WDDM 2 AFR is really not a big deal to handle, much of the code needed to run it is provided by the Windows 10 operating system itself. In practice, a smaller implementation needs to be written for this, which gives access to DMA engines, and Microsoft allows vendors to use frame pacing, which displays the computed frames evenly. Incidentally, this can be done by the application itself, so it is not mandatory to address the issue on the drive side. However, since the system itself is standard, you no longer need drive profiles for multiple GPUs, if your game supports WDDM 2 AFR, it will simply work with a device driver released several months earlier.

An added benefit is that from now on you won’t have to look at licenses on motherboards. Simply put, if you have two full-width PCI Express ports on that board, you will definitely support multi-GPU modes for explicit APIs. You just have to make sure that the two VGAs are similar. It is optimal if it is the same, but if the device ID is the same, it is enough for the system to work.

In addition to WDDM 2 AFR, DirectX 12 and the Vulkan API also offer alternative solutions. The former is simply the easiest way, since some of the code is written within the operating system. In linked mode, the code can be provided by the application anyway, so there is a lot of freedom in this respect, but in this case it is mandatory to solve the frame pacing itself within the program code.

Regardless of the linked mode used, many games support Halo Wars 2 (DirectX 12), Battlefield 1 (DirectX 12), Gears of War 4 (DirectX 12), Rise of the Tomb Raider (DirectX 12), among others. , Shadow of the Tomb Raider (DirectX 12), Hitman (DirectX 12), Deus Ex: Mankind Divided (DirectX 12), Sniper Elite 4 (DirectX 12), Strange Brigade (DirectX 12 and Vulkan), Zombie Army 4: Dead War (DirectX 12 and Vulkan), Red Dead Redemption 2 (Vulkan) and Quake RTX (Vulkan).

Unlinked mode, also known as explicit multiadapter, is more complex than the above model. The point is that you can handle the available resources very freely. In this system, the application can distribute tasks between GPUs in any way, and they are not necessarily required to have similar performance or possibly come from a vendor, they also depend on the decisions made on the program side. This multi-GPU mode, of course, is not as common, it is essentially used by Ashes of the Singularity: Escalation (DirectX 12 and Vulkan) and Civilization VI (DirectX 12), both programs in different formats.

Which is to say that the above games work amazingly well on multiple GPU configurations. It’s as good as you could have dreamed of with the old CrossFire and SLI options, so there’s massive potential in the system provided by the new explicit APIs. It is possible that an era is over with the execution of old solutions, but a new one begins with fresh possibilities. The multi-GPU direction may undoubtedly seem to be on the verge of death, but it cannot be ruled out that they are only really being born now. For example, the launch of obsolete APIs frees up significant resources for developers, some of which can be devoted to researching these new capabilities, as well as companies designing GPUs.

Source: Hírek és cikkek – PROHARDVER! by prohardver.hu.

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