Just wondering about SLI Support. I never bothered with before, since none of the games I play supported it. However, thats about to change with the next update to ROF.
Im still on the fence if it will be worth adding a 2nd card. MY current card (460 GTX with 1 GB ram) seems to run ROF nicely with all settings maxed except shadows, which I have set to special medium. Im using 92% ram. ROF plays very smooth, no stuttering or CTD's. Very high FPS.

Now if I get a second 460, will That double the video ram? ie, will ROF launcher say Im using less ram because there is a second card with another 1GB ram? I know we dont have the update yet, so its just speculation at this point, but for those of you with SLI, if a game supports it, is their a big difference in Frame rate with it?

Will it cause non SLI supported games to run slower?

Rob

The question of SLI "support" seems to be incredibly misunderstood...

First of all, there is absolutely no *requirement* for any game to "support" SLI - you can get benefits of running multiple graphics cards in an SLI arrangement, regardless of a given game "supporting" it.

In fact, SLI configurations offer several modes specifically designed to benefit games that *don't* have integral SLI support (which should pretty much tell you that SLI "support" is not necessary).

About the only difference is whether a game has built-in configuration for taking advantage of features, or whether you have to set these features yourself, externally (using, for example, the Nvidia control panel app). It's done using "profiles", which (to answer another question) can either be assigned globally or to each individual app.

Running a number of cards in SLI does not increase usable graphics memory available to the applications (games). If, for example, you use 2 cards, each with 1GB memory, your total memory in SLI configuration would still be 1G.

Running two cards in SLI will not double your performance (nor will three triple it, etc); that's never been the claim or the intent. Some games do much better than others; generally you might expect around 50% improvement - but I'll tell you right now, it varies widely. SLI was not intended to offer performance gains at a rate proportional to the number of cards you add.

SLI only 'makes sense' from a 'bang-for-the-buck' perspective in certain scenarios, and because cost is a big factor (and costs change with time), timing also plays into it as well. It's sometimes better to buy one higher-end card than two lesser cards in SLI; but there are still instances where running two cards makes more sense. If you find yourself considering it, one way to help resolve questions is to find out what a new, higher-end card would cost compared to another like you have; then search online for comparisons (2x cardX v. 1x cardY). There are lots of these comparisons out there, and also plenty of articles on what you should (and should not) expect from SLI.

I'm sure there will be plenty to come along and say I'm wrong - so, rather than argue with uninformed folks here, I'd simply go over to Nvidia's website, and check it out for yourself.

Incidentally, I have owned/run three different SLI configurations over the past several years (and on three different systems); 8600GTs, 8800GSs, and 9800GTs. There *is* a difference, and it can be fairly substantial. Although SLI has been blamed for several problems, over the course of time I experimented with different setups, I conclusively proved (at least to my own satisfaction) that SLI wasn't causing *any* problems on my machines.

It always struck me as interesting (and somewhat amusing) that, of all the people who know so much about SLI, and all the problems they talk about, few if any of them ever actually owned it or worked with it at all.

Ya know, sometimes ya almost set yourself up when ya say this....



- but then when you follow up with something like this; all I can say is Bravo! Best advice i've read all day!

Ya know, if more folks did the later....they wouldn't be such good candidates for the former.

Always best to go to the source instead of listening to peers....

That clears up some missunderstandings I had about SLI. Thanks for responding.
Ill wait and see if I have any performance issues after the next update and take it from there.

Thanks again,

Rob

SLI and Crossfire support is not something the vendors (Nvidia or AMD) have to create for games using profiles etc. As long as the developers programming the games use the correct guidelines as set down by Nvidia, AMD and even MS (DirectX) then games should benefit from multi GPU setups. Profiles from vendors are built in to drivers to enhance or tweak an already working game.

Sometimes games are programmed in such a way as to inadvertently create bad results with multi GPU setup, even negative scaling is noticed in some games. CoD, RoF, DCS-A10C are three that cause problems on my Crossfire setup, such as graphical glitches, negative scaling (slower on two cards than with one). I had an SLI setup with 2X GTX 460s and RoF would give BSODs and graphical problems unless I disabled SLI. So, yes SLI or Crossfire CAN indeed be the cause of serious graphical problems in lots of games. Though my experience it is the fault of the game and how it was programmed and not SLI or Croffire.

Here for example, the same issues I had with both SLI and Crossfire in RoF.

http://riseofflight.com/forum/viewtopic.php?f=265&t=12934

There will be SLI and CFx support for RoF and CoD in the future. The advantage you will have is that you can go for an extra secound hand [=cheap] GTX460, to reach a higher performance level without paying the max price.
Do your readings on http://www.tomshardware.com/reviews/crossfire-sli-3-way-scaling,2865.html
http://www.tomshardware.co.uk/forum/245454-15-crossfire-faqs

Only keep in your mind that some games do not like SLI or CFx mode, your PSU should be capable to handle the extra power and your mobo must support it!!!

GPU scalability has been significantly improved since its beginning.Right now Im using 2 5850's in crossfire and in most games I get around 80%-90% performance gain,so thats pretty close to doubling your fps.Though it doesnt work that way in a few games,or it just doesnt work at all.

Memory usage with or without Crossfire (2xHD5850). RoF will not even start with everything cranked up in non-crossfire. Starts and flys smooth with crossfire on full settings. I do see a difference in performance using Crossfire but I beleive it is due to the program seeing one card with twice the memory. Yep,I am one of those uneducated Neophytes but I do beleive what I can see, and I see a difference.

With Crossfire enabled


Without Crossfire enabled

PropNut...your experience may be entirely different with CrossFire - please note my entire post above specifies "SLI". Perhaps Crossfire does allow apps to "see" the total memory of both cards - SLI does not. This has always been the case, and it is well-documented on the Nvidia website, as I mentioned.

I'd also be very curious to see how the video memory itself is reported elsewhere, other than the percentage RoF displays (which, to be honest, I don't think anyone can truly explain in any detail).

(I will confess a slight envy if it winds up that somehow CrossFire excels in this area, but I've always been an Nvidia user myself).

Best of luck to you.

Good point. I was going to mention that I had two 9600GSO cards in my simpit and the results were the same, pertaining to memory. Unfortunatly I no longer have my simpit set up (using a rollout simpit in my office now) so I could not provide emperical evidence of my assertions, hence I only discussed crossfire.

The OP asked specifically about SLI but I think the information that we can learn in threads like these are important to users of both technologies.

Would you post screenshots of RoF memory usage in SLI? I am curious if it is the same with both Crossfire and SLI.

I switch back and forth, I like both Nvidia and ATI. Right now ATI is winning for me as they have three monitor support with a single GPU and I do like Eyefinity

Interesting stuff! Thanks to all for posting their results and experiences with SLI.

What propnut posted, is what I hoped would be the case for Nvidia SLI. (sorry to hear it doesn't work that way) I too am an Nvidia user. I have no intentions of spending $500 plus on a new 580 card, but $200 for a second 460, would be an option. My motherboard and power supply are both SLI ready and all Id have to do is pop one in. With a single overclocked 460, Im getting 50-55 FPS in ROF with all setting maxed and memory usage at 92%.

If I add a second 460, It would be worth it, if memory usage dropped down to say 65% or something like that. Based on what Im reading, that would only happen in crossfire but not Nvidia SLI. So SLI would not lower memory usage on the ROF start application, but like Knowbreaks said, we dont really know how that works.

SLI should give me some increase in FPS. How much,is debatable. maybe a 20-30% increase would be realistic? Maybe more, maybe less. With the 50-55 fps that I get currently, Im not sure Ill care if I get 65-70 with SLI. I dont know if I will notice the difference. all my other games are running great too, so right now, I dont really see the need for SLI. However $200 for another card is not a big deal, so I may just pick one up for the heck of it. I like to tinker and it will give me something to play with.

One last question, If I get another card, and it causes an issue with another game, ie graphics issues or crashes, can it be disabled in the nvidia menu easily?

Rob

Everyone just chill a bit. SLI and Crossfire coming with 1.019.

Jason

Best news I've heard all day! I've got a CrossfireX setup.

I second the issues encountered in DCS games... Sad stuff with CrossfireX.

How long is a bit?

Its now confirmed 1.019 in 2 weeks!

Be Sure!