How do I go about getting SL to recognize crossfire video card set ups?

[Jericho Foehammer]

I have a trio of 6950 2gb video cards to play with for a while, and I'm wondering if there's anyway I can get SL to recognize at least two of them in 2 way 16x crossfire. Any help would be greatly appreciated :)

[Peggy Paperdoll]

SL already "recognizes" Crossfire or SLI.  It's the video processing power that two or more vdeo cards provide.  But there is a limit to just how much can be brought to your monitor when 99% of the content you see is user created (amateur created).

[OneOf Titian]

From what I have read there isn't a simple way to do so (but there is). Also, I've read the rendering engine of SL is apparently single threaded, therefore it doesn't matter if you have 1 or 4 GPU, it will still only utilize one core.

Most of the time FPS dips, is when it's pulling data from the SL servers. Until we all have gigabit internet there will always be momentary hang/lag because SL is like 3D internet, each sim is like a 3D webpage, and like a webpage the content is dynamic, changing all the time. So it always has to pull new from the server. It's not like WoW where all the realm data is on your computer and the only thing being transmitted is Player and NPC data; in SL everything is being loaded all the time, though you could make your SL cache space bigger. The only time I ever have a hiccup is at the same time as something reading/writing to the drive, though an SSD would probably mostly fix that. 

I'm going to try some of these tricks for getting OpenGL apps to use multi-gpu that I found in this article linked below. Probably wont work, but we'll see. Of course it's good to have Afterburner OSD so you can see if the load is being distributed or not. The real shortcoming is that most applications "must" be in fullscreen mode to work in SLI/CFX and SL has no such setting.   http://www.geeks3d.com/20101209/tips-how-to-enable-sli-and-crossfire-support-for-opengl-applications/

UPDATE: (next day from post date) So I loaded an other SL client, Phoenix Firestorm, which will run in Fullscreen, though I've also found that fullscreen is a little irrelevent, aside from making it so that GPUs can focus on one task. Irrelevent, as the CrossfireX seems to work in windowed mode with this app. I followed the advice in the tutorial linked above, and renamed the Firestorm executable(.exe) (not the shortcut,) to an app name that has a CrossfireX profile, oppened it and bob's-your-uncle, it works. Shows a bout a 50/50 load split per GPU load, everthing in graphics settings set to full 30+FPS. Best thing ever, I've never seen SL render this good before. If there isn't much happening on screen it even run up around 60fps. I haven't tried the file rename with the native SL viewer yet, but I will.  :matte-motes-big-grin-squint:

Also, another trick for boosting performance is to create a RAM disk and have it load the SL cache there, this of course is only plausible if you have 8Gb+ of RAM to start. You have to have enough to support your system, and it's SWAP file, and still run the RAM disk. This also extends the life of SSDs. There is a little article over that the Catnip SL viewer website on doing this, http://catznip.com/2013/02/23/speeding-up-sl-with-a-ramdisk/ Really great tips though. I hope this was all helpfull to anyone looking to CrossfireX or RAMDisk their SL viewer for (way) better performance. 

Another thing for bosting performance of the viewer that I found. Enlarging the downstream, Rx, Incoming NIC buffer. Some Network Interface Cards will let you change this in the device driver settings/properties, found in the Device Manager in Windows. It's rather small really, set to about 256Kb default on mine, I upped mine to 2,047Kb(max) aka 2Mb. Which may seem small, but in SL a lot of what you load is big stuff, so 2Mb is a huge differenc over 256Kb. 

[OneOf Titian]

I've updated my post, it is possible, there just isn't much info out-here that directly correlates.