Performance gain by SLI

[Sigurd44]

As topic, I ordered a second Asus 670 GTX 4 GB VRAM a few hours before (I have the money, so it's not only for Skyrim). What performance gain can be expected by using two Asus 670 GTX 4GB VRAM instead of only one?

 

At moment I have around 15 to 30 fps (depends on area) with a heavy mod loaded Skyrim, uGridtoLoad 7, shadows at 4096, 1920 x 1080 resolution.

 

In theory it should double the fps, in theory...

 

My aim is to play at 2560 x 1440 resolution with around 20 to 30 fps left :-)

[FiftyTifty]

Anywhere from 10%-70% performance increase in the few games that support SLI.

In the vast majority of games that don't, performance will be impacted HEAVILY.

 

Hell, if you just turned down the shadows, you'd be in the smooth 60fps range with a single 670.

[Zalman1337]

That's why I don't like SLI: so many games don't support it and you rarely notice the difference. It just isn't worth it, in my experience (you're better off with getting one really good video card instead of wasting money on 2).

[guReMcO]

I have 2 Asus GTX560Ti cards in SLI and although I can't give you FPS numbers I'd say it doesn't do anything for Skyrim. I played it on one card then turned on SLI and noticed no difference in performance. There was no obvious boost in fps it might have made it a bit smoother but it's not worth getting a SLI setup for Skyrim. That's my experience anyway.

[nosisab]

I have 2 Asus GTX560Ti cards in SLI and although I can't give you FPS numbers I'd say it doesn't do anything for Skyrim. I played it on one card then turned on SLI and noticed no difference in performance. There was no obvious boost in fps it might have made it a bit smoother but it's not worth getting a SLI setup for Skyrim. That's my experience anyway.

Something is wrong in your SLI setup or are playing with very conservative graphics quality. SLI like Crossfire also, matured a lot lately.

 

Coincidentally I ran a series of 3DMark benchmarks, the 3DMark vantage, 3DMark 11 and the newer 2013 against two Intel CPU powered friends rigs, the first with a GTX 480 and the second with a GTX 570. The results were interesting, mainly from the first test on the 2013 version of 3DMark.

 

This test is a very light test meant for entry level machines, the FPS went crazy, with a median of 700 FPS and surpassing 1000FPS in parts of it... the end result showed a total score doubled for the two machines over mine in all modes, graphics, physics and combined.

 

The second test, meant to mainstream machines and relatively powerful laptops did balance things, with slight advantage of the GTS 560 SLI over the GTX 480 and GTX 570, and slight lower performnance on physics (which were done on the CPU and then the Intel iCore has a clear advantage over the bulldozer), the combined test was bad, falling bellow 20.

 

The third test, meant to high end machines is really heavy but it returned a significant advantage for the SLI all the while keeping the equilibrium (bad) toward physics and totally unplayable combined mode below 10 FPS.

 

These results were consistent with the expected from the other two older versions also, with advantage for the SLI albeit not a big one.

 

Conclusion: Most of games of today have SLI support and then they get huge advantage over a single card setup. Some games still benefits from the generic SLI even when not having specific SLI profile. And some few games don't get any advantage from SLI and some may force you to disable the second card at all due to possible glitches.

 

To the first type the gain is around 80-90% over the single card performance, to the second it is variable but from experience I'd say it's is around 50% min.

 

So, if planning to build from scratch is advised you go for a single, most powerful card nearest the cost of the two intended for the SLI.

 

If you already have a card able to SLI and is not planing a huge leap to a very powerful and expensive card, the SLI is the best option budgetwise and even performance wise when comparing with the next card on the category (for example, two 560 is better than one 570 and two 570 better than one 580... the same may still be valid for the 6xx series).

 

I can't really say about the Crossfire but imagine it to be similar.

 

Edit: Must be understood than the amount of VRAM does not double on the SLI, if each card has 1GB VRAM, this is the total amount seen by the system.

Edited February 7, 2013 by nosisab

[guReMcO]

Maybe I'm hitting a vram limit then because Skyrim doesn't seem affected by SLI. A lot of my other games are, Battlefield 3 for instance runs like a dream with SLI.

[BallaTheFeared]

If you're already getting 60 fps, or smooth framerates, adding a second card won't do anything for you.

 

 

If you're using a lot of IQ mods and lighting/SSOO/DOF/grass/shadows, you might benefit from an additional card.

[Sigurd44]

If you're already getting 60 fps, or smooth framerates, adding a second card won't do anything for you.

 

 

If you're using a lot of IQ mods and lighting/SSOO/DOF/grass/shadows, you might benefit from an additional card.

 

I definitly benefitted from a second 670 GTX. I had around 25 fps before at 1920 x 1080 resolution and maybe 15 fps at 2560 x 1440.

Now I have 45 fps at 2560 x 1440 resolution.

 

My god, this mod loaded (around 50 texture mods, most are 4k resolution and even higher) and heavy .ini tweaked (4096 shadow resolution, uGridtoLoad 7/64, LODs at 20, all selfshadowing and water enhancements on) Skyrim, on absolutley ultra grafic settings (16 AF, 8 AA, 8 Transparency AA, Ambient Occlusion/On High Quality, FXAA), playable with 45 fps on 2560 x 1440 is just awesome.

 

The fps has more than doubled...could it be that SLI mode has more effect for higher resolutions? Before I had 15-20 fps and it lagged as hell, was only good for screenshots, now I can actually play the game at 45 fps. It's the same scene (my standard save place in my house in Heljarchen, same actors/NPCs in my view as before), the same mods and the same settings.

 

Have to say IF (!) a game supports SLI and you have a display that is able to show higher resolutions as 1920 x 1080, SLI seems to rock, at least for Skyrim.

 

Now there is just one problem left. Usually overclocking GPUs (moderately overclocked, + 120 gpu clock, + 100 mem clock) with EGVA precision x can adjusted to "synchronized", so your overcklcking setup and the fan curve should be mirrored, but one card gets much hotter as the other.

[DumbNewbie]

I know this is a pretty old topic, but my question seemed fitting here.

 

I have two GTX 690's (so quad SLI capability); however, the more gpu's I have linked, my FPS actually decreases, which makes the "SLI disabled" give the highest FPS by quite a bit (roughly 35 to 40 FPS disabled compared to about 15 to 20 FPS with quad SLI enabled).

 

I could possibly understand no change in performance, but not such a significant decrease. Can anyone shed some light on why this might be, and maybe give a possible solution? If it helps, my signature has a bit more information on my rig, and the mods I use are what's suggested at Skyrim Beautification Project with Realism ENB.

[Boombro]

Skyrim doesn't work well with SLI. It just doesn't support it. Even worse with ENB.

As far as I know.

Edited December 27, 2015 by Boombro