The latest version of IL-2 has received a hotfix designed to solve several problems that cropped up. Among them are wind corrections for career and advanced quick mission builder modes as well as a fix to an aspect ratio problem on the HTC Vive Pro 2 VR headset. There’s also the issue of SLI support which has become a significant problem. There’s a statement about it that has just come out. Let’s go check this out.

Hotfix time

Some IL-2 updates need a hotfix and this is one of them. Released less than an hour ago, the hotfix contains updates for wind, VR, precipitation in certain cloud scenarios, and quite unfortunately the removal of SLI support. Here’s the official list of updates:

• Wind restored in Career and AQMG modes;
• Haze restored in Career and AQMG modes;
• Wrong aspect ratio corrected on HTC Vive Pro 2 VR headset (and possibly others that have non-square pixels);
• P-51D improvements by Oyster_KAI: propeller, gyro horizon indicator (AN-5736-1), Detrola (BC-1206) beam approach system, radio rack placards (SCR-522);
• Stalingrad smokes are correctly oriented by the wind;
• Fixed ‘cut clouds tiling’ on some maps;
• Rain added to 04_overcast_08 cloud pattern, some other patterns are tuned;
• Surface editing functionality was restored in Mission Editor because of the popular demand.
• SLI/Crossfire option removed from the GUI due to incompatibility with the new clouds technology. The option remains in the Launcher for now and in startup.cfg. You can read Jason’s comments on it here. 

SLI removal

Scalable Link Interface (SLI), an nVidia technology has been used together with CrossFire for several generations of GPU. Allowing people to link two GPUs together, the idea was that two cards could boost performance when run together. The reality has been somewhat more complex as successive generations of cards have struggled to make the idea a full reality and many games struggled to offer support.

SLI was formally replaced with NVLink a few years ago but even that is now limited to just the very high end RTX 3090 and nVidia Quadro cards. SLI has stopped being supported by many games (and by nVidia) and the technology seems to be dying a slow death. IL-2 has supported it up to now but that support is ending.

In a post by Jason Williams, 1CGS apologizes that support is being dropped explaining that the new cloud technology isn’t fully compatible with SLI.

I want to take a few seconds to explain the situation with multi-GPU support (SLI/Crossfire) and our new clouds technology. Unfortunately, as some of you who have SLI or Crossfire setups have learned, our new cloud technology is fundamentally incompatible with multi-GPU machines. And I want to apologize to those that are affected by this because we failed to inform you prior to the 4.701 release. This was an oversight on our part and we sincerely apologize for the surprise. Also, our lead programmer has looked at this issue several times, and he reports that there is no way to make it compatible with the new clouds. In order to remain competitive, we needed to re-vamp our clouds, but an unfortunate side-effect was this issue. We often have to make hard decisions about compatibility and technology and we dislike such choices, but they are part of the business.

Jason Williams

Jason goes on to explain their plans including news that formal SLI support is being dropped in 4.701b (out today). However, they are leaving the option in config files should a solution to the SLI problems be found by workaround. So its not completely gone but it is on the way out.

The dream of multi-GPU may not yet be dead as there are other efforts on the way to be able to tap into the promise of multiple GPUs. DirectX12 (not currently supported by IL2) for example has support to make use of more than one graphics card and that may ultimately be a new generation of this technology. Meanwhile, many other PC titles have dropped support altogether and it seems that IL-2 was one of the remaining holdouts.

SLI has always been a niche but I do feel for folks who were using this system and are now potentially loosing a bit of performance. Unfortunately times change and technology moves on and SLI is one of those technologies that is slowly being consigned to the history books.