The SLI information guide

[D2ultima]

Heyyo,

Good guide. The only recommendation I'd add? A link to this table of user-found SLI bits. It's quite the comprehensive list of SLI bits for either better SLI scaling or support for SLI in games that don't have it.

http://www.forum-3dcenter.org/vbulletin/showthread.php?t=509912

and of course in order to use those bits the program NVIDIA Inspector is needed.

Sure, I'll add it in. I'm always glad to expand the guide some.

[Chuck13198]

So say I want to dual SLI. I currently have a gtx 780 from evga superclocked. Is it possible for me to dual sli with cards from the new 900 series? I just want to know if it's possible to dual sli with anything better than a gtx 780 in the nvidia lineup

[D2ultima]

So say I want to dual SLI. I currently have a gtx 780 from evga superclocked. Is it possible for me to dual sli with cards from the new 900 series? I just want to know if it's possible to dual sli with anything better than a gtx 780 in the nvidia lineup

What can I SLI?

 

You:

CAN use mismatched cards if you are driving a second or third monitor from the extra card. I believe this does not even need a SLI bridge.

CAN use mismatched cards if you are driving PhysX on the second card.

CAN use the same cards in non-performance-boosting mode (driving extra monitors) to do triple monitor gaming.

CAN use cards with different core clock speeds in SLI without one card being slowed to match the other.

CAN use cards with different memory clock speeds in SLI without one card being slowed to match the other.

CAN use cards from different manufacturers as long as their specs are the same (I.E. "MSI GTX 780 lightning" + "Gigabyte GTX 780 Windforce" will work).

CAN use cards with different forms of cooling in SLI (reference cooler + non-reference cooler).

 

MAYBE can use mismatched cards driving extra monitors for triple monitor gaming (I do not know, so I am leaving it as a maybe. ANYBODY who can test and let me know, please do.)

MAYBE can use mismatched cards to force higher levels of CSAA (like 64x CSAA) on games. As above, I cannot test it.

 

CANNOT use mismatched cards in performance boosting mode.

CANNOT use cards with different cores even if the same name (GK104 GTX 660 (OEM) + GK106 GTX 660 will fail).

CANNOT use cards with different vRAM sizes even if the name and core is the same (GTX 770 4GB + GTX 770 2GB will fail).

CANNOT use cards with different memory bus width even if the same name and core is the same (GTX 760 192-bit (OEM) + GTX 760 256-bit will fail)

The only way you'd be able to use the 780 is as a PhysX card or to run extra monitors.

[D2ultima]

I've updated quite a bit of this guide with information I've verified lately. It's enough information that I think it's worth a bump.

[D2ultima]

Oh yeah, that link you provided of the notebookreview forum, it was very, very helpful. I really didn't notice that thing at all, even though I read Maxwell's review on Tom's Hardware. That's another thanks for you. Nice going!!!!

Not a problem, that's what these guides are for. When DX12 is out and running full steam I bet I'm going to need to make a lot of changes to this >_<. Aaaand now to handle HBM on the vRAM guide.

[ConnorDahne]

I have a couple questions if anyone cares to help me out??
I just ordered a second 970, and this will be my first SLI rig.
How well does gsync work with SLI??
My gsync monitor has killed all the lag and screen tearing I had, and I was hoping that it might help with micro stutters associated with SLI.
I haven't been able to find any current info on it??
I saw people say its awful a year ago, then others say its fixed?
I also got myself a new board, because my old one wasn't "SLI Ready"
It had 16x and 8x, would I have been fine using 16 and 8?? lol
Not sure if i want to know lol

[D2ultima]

How well does gsync work with SLI??

My gsync monitor has killed all the lag and screen tearing I had, and I was hoping that it might help with micro stutters associated with SLI.

I saw people say its awful a year ago, then others say its fixed?

It had 16x and 8x, would I have been fine using 16 and 8?? lol

From what I know, it should work fine right now.

SLI has no microstutters unless your FPS is very low, so I don't know what microstutters you're attempting to kill... unless you plan to run your game at 35fps?

Cannot comment on that.

Since a consumer intel board only has 16 PCI/e lanes, then you'd never have gotten 16x + 8x. You'd get 8x and 8x, and that's fine for SLI. If you're on an AMD board, then you should have more than enough lanes, though I'd quicker tell you to buy a new intel board.

 

I would suggest you buy a single 980Ti instead of two 970s, as per my recommendation section of this guide. SLI is not being supported as well as it was a couple years ago by devs' interests and by nVidia's tech.

[ConnorDahne]

I already had a 970, so it was a little cheaper to grab a second 970.
I don't plan on runninng fps anywhere near that low, so that's awesome to hear.
If you don't mind me asking yet another question, what is the point in the more expensive SLI board versus the non SLI then??
I went from http://www.newegg.com/Product/Product.aspx?Item=N82E16813128713 to http://www.newegg.com/Product/Product.aspx?Item=N82E16813130771
Thanks for your help, I really appreciate it

[D2ultima]

I already had a 970, so it was a little cheaper to grab a second 970.

If you don't mind me asking yet another question, what is the point in the more expensive SLI board versus the non SLI then??

I went from http://www.newegg.com/Product/Product.aspx?Item=N82E16813128713 to http://www.newegg.com/Product/Product.aspx?Item=N82E16813130771

Thanks for your help, I really appreciate it

Well you would get more raw power that way anyway in games that support it... still a single 980Ti would do you better though.

Some non-SLI boards don't have a second PCI/e x16 slot, and some even if they have it, aren't configured to run it at 8x to allow for 8x/8x configs necessary for SLI. AMD can use 4x for Crossfire, so a board can be "crossfire capable" without being "SLI capable".

From what I see, there's absolutely no reason for you to have changed motherboards. Going by the spec sheet provided on Newegg, that is. Of course, know that boards have different VRM types etc that might affect CPU overclocking and the like, but I'm not very well versed in those particulars.

[ConnorDahne]

Well crap.
I stumbled onto Linus's video about pcie lanes after I ordered it, and started to second guess my decision.
Atleast this one matches my 970's colors I guess lol
Thanks for clearing that up for me.
Have a great day!

[ThE_MarD]

Heyyo,

One exception to the SLI VRAM rule? It can "work" with different VRAM amounts but there is the risk of crashing.

DifferentSLIAuto has worked for some users, heck, even for some they could get SLI on non-SLI certified boards... but of course, it's at that users discretion.

I mainly recommend DifferentSLIAuto to users who have two GTX 970s but it won't allow them to enable SLI.

https://github.com/EmberVulpix/DifferentSLIAuto/releases

At least one user on these forums have gotten it to work with different VRAM GPUS.

http://linustechtips.com/main/topic/166992-gtx-760-sli-not-working/?p=2222303

[D2ultima]

-snip-

Mmm... I'll consider that. I might warn against betting on it and linking to it, but allude to its existence, similar to how I did it with the SLI on/off situation for laptops (which I do use).

[D2ultima]

And how long did it take you to make this? Excellent job, I know a lot more then I did. 

80% of the information in the guide was created just from me using SLI on my notebook with various games and talking to a couple other SLI notebook owners over the course of about 8 months.

 

The remaining 20% was discovered after; 10% being data collected from other users (as I don't have maxwell video cards, or SLI on desktops) and 10% just people correcting my information on other forums.

[D2ultima]

LOL it adds up to 120%, the amount of Hz in your monitor.

What? No... of the final 20%, 1/2 (10%) was from other users who had setups I could not check, and the other 1/2 was from users who told me "you're not exactly right with <statement I just made>"

[GER_T4IGA]

Did you talk about micro stuttering anywhere. I read everything that could have contained that section. Maybe I am to tired but then I'd like you to show me where it is.

I had been tinkering with getting an SLI confit but I am sooooo solo afraid of the stutter since I am very sensitive to fps drops, dips, varying frame times, etc.

Edit: you are officially allowed to put the tl;dr stamp on my face. I just read the 2. Page.

So micro stutter is not really a thing anymore? Wow... That is ... AMAZING!!

[D2ultima]

Did you talk about micro stuttering anywhere. I read everything that could have contained that section. Maybe I am to tired but then I'd like you to show me where it is.

I had been tinkering with getting an SLI confit but I am sooooo solo afraid of the stutter since I am very sensitive to fps drops, dips, varying frame times, etc.

Edit: you are officially allowed to put the tl;dr stamp on my face. I just read the 2. Page.

So micro stutter is not really a thing anymore? Wow... That is ... AMAZING!!

Actually, it usually happens around 30-35fps. It's especially bad in GTA V's main menu before you load story or online mode because it's locked to 30fps .

 

Once you're at say... 40fps or above, you'll experience no microstuttering unless the game needs a lot of optimization.

 

I had considered adding it into the guide before... but most users don't play at 35fps in SLI. I think I'll add it in the top part, where I clear misconceptions. Thanks for reminding me!

[GER_T4IGA]

Actually, it usually happens around 30-35fps. It's especially bad in GTA V's main menu before you load story or online mode because it's locked to 30fps .

Once you're at say... 40fps or above, you'll experience no microstuttering unless the game needs a lot of optimization.

I had considered adding it into the guide before... but most users don't play at 35fps in SLI. I think I'll add it in the top part, where I clear misconceptions. Thanks for reminding me!

It would be nice to have in there what you just told me.

[D2ultima]

It would be nice to have in there what you just told me.

I added it, it's in the misconceptions section now. 

[shadowr1ku]

I was planning to go SLI 980's when I get my 1440p Monitor but reading this information, I am kinda worried to do so. First world problems lol

[D2ultima]

I was planning to go SLI 980's when I get my 1440p Monitor but reading this information, I am kinda worried to do so. First world problems lol

980Ti first. I can't stress that enough right now. Next thing you know you buy three unreal engine 4 games (like Ark Survival Evolved being one) and all of a sudden you're on a single 980 again.

 

I don't know why engines like UE4 are bringing out such intense visual effects and then killing SLI support, but it is what it is. Even Kojima's Fox Engine, as nice as it is, doesn't love SLI all that much. Nobody ever said anything about it, but MGSV: GZ seems to cap out near ~75% util on each GPU. Or games take many months before they work really well with SLI now.

 

I don't think two 980s is particularly a bad option, but considering the boost that a single 980Ti grants and the little price difference, it's a no brainer. If the 980s were $400, it would be different. The R9 390X cards are ~$420, yes, but lack of windowed mode support in Crossfire and lack of overclockability on the AMD cards prove it less desirable to be a card to run in multi-GPU states.

 

So I just tell people to get a 980Ti first before even considering multi-GPU. I would recommend the Fury X as a 980Ti alternative, but it seems to have some low util problems, and regardless of what anybody says, that 4GB can be an annoyance with the amount of power that the cards can crank out (high resolutions + high levels of multisample-type AA are a desirable thing, regardless of what anybody else says, far less those who use multiple monitors and have Windows use up some of their vRAM too).

[shadowr1ku]

980Ti first. I can't stress that enough right now. Next thing you know you buy three unreal engine 4 games (like Ark Survival Evolved being one) and all of a sudden you're on a single 980 again.

 

I don't know why engines like UE4 are bringing out such intense visual effects and then killing SLI support, but it is what it is. Even Kojima's Fox Engine, as nice as it is, doesn't love SLI all that much. Nobody ever said anything about it, but MGSV: GZ seems to cap out near ~75% util on each GPU. Or games take many months before they work really well with SLI now.

 

I don't think two 980s is particularly a bad option, but considering the boost that a single 980Ti grants and the little price difference, it's a no brainer. If the 980s were $400, it would be different. The R9 390X cards are ~$420, yes, but lack of windowed mode support in Crossfire and lack of overclockability on the AMD cards prove it less desirable to be a card to run in multi-GPU states.

 

So I just tell people to get a 980Ti first before even considering multi-GPU. I would recommend the Fury X as a 980Ti alternative, but it seems to have some low util problems, and regardless of what anybody says, that 4GB can be an annoyance with the amount of power that the cards can crank out (high resolutions + high levels of multisample-type AA are a desirable thing, regardless of what anybody else says, far less those who use multiple monitors and have Windows use up some of their vRAM too).

 

I am glad you gave me such insight, so I will attempt to get on that 980ti. I guess because the market right now is console gaming, and since obviously consoles don't have

 

SLI/Crossfire companies don't bother optimizing profiles from the start. I find that rather annoying but at a business perspective it makes sense. Someone on reddit

 

suggest going Crossfire 390x's but the power output worried me a bit.

[GER_T4IGA]

-snip-

Just quoting you because I have aquestion?

Do you think the GTX 770 would be fast enough to do PhysX for a GTX 980 Ti? Probably on the edge, or is it just fine?

[D2ultima]

Just quoting you because I have aquestion?

Do you think the GTX 770 would be fast enough to do PhysX for a GTX 980 Ti? Probably on the edge, or is it just fine?

I think it should be. I also have this followed so you can reply normally and I'll see it in my mentions. I'm a little OCD so I keep my mentions clean .

 

 

I am glad you gave me such insight, so I will attempt to get on that 980ti. I guess because the market right now is console gaming, and since obviously consoles don't have

 

SLI/Crossfire companies don't bother optimizing profiles from the start. I find that rather annoying but at a business perspective it makes sense. 

It's not about the consoles... it's just how the market is heading. The current-gen consoles triggered a string of unoptimization for reasons unknown. Like, before, devs had to squish memory down hard to make them fit on the last-gen consoles. So even if they wanted to be sloppy with the PC, we could usually brute-force it. But now they have oodles of memory and such, and they can fit in a lot more effects by still focusing on lower framerates.

 

The first sloppiness went straight into vRAM. "High resolution every texture ever! I don't care if it makes sense to have a 2048 x 2048 helmet texture as well as a 2048 x 2048 body texture! DO IT! AND MAKE THEM SHOES 4096 x 4096!" or something like that. Since that craze is over because they realized the whole world doesn't have 6GB and 8GB GPUs, and that high resolution textures doesn't make them look better/less muddy (just sharper), we've now encountered the "DEVOUR THE CPU! DEVOUR IT! WE'LL WAIT FOR DX12 AND UNTIL THEN WE'RE GONNA JUST EAT YOUR CPU FOR BREAKFAST!" stage. It sucks because unlike tossing high vRAM GPUs or more GPUs or whatever at the problem (which is a shitty way to deal with it), better CPUs don't exist when you already have a modern i7 that maxes near 100% load and can't even give 120fps in CoD BO3's beta on min graphics. Not that max graphics lowers the FPS any, because it's CPU limited >_>. Watch, I bet next we're gonna get RAM limited and everyone'll need 32GB instead of 8GB for recommended gaming.

 

Anyway. The reason for lack of SLI support is beyond me. Most of the new stuff nVidia are touting lacks SLI support (like MFAA) or has somewhat bad SLI support (like virtual reality) even though previous tech which was supposed to have the same limitations for multiGPU (like temporal filter AA) was circumvented by them (TXAA). A lot of new tech DOES require that AFR is not used, but I find it really stupid for things like Unreal Engine 4 to cut out SLI support AND REMOVE OTHER ADVANCED VISUAL TECH FROM ITSELF because "PCs wouldn't be strong enough to run it". It's like... you're cutting out the way to get the power, then complaining that nobody has the power. Explain.

 

TL;DR? I have no idea why SLI support is waning or sucking or people are utilizing it badly in games, but I don't think it's directly related to the consoles. I think they more just don't care anymore, and I can't say it's getting a lot of love from nVidia in the first place. I can't even consider AMD's option until it works in windowed mode either.

[shadowr1ku]

I think it should be. I also have this followed so you can reply normally and I'll see it in my mentions. I'm a little OCD so I keep my mentions clean .

 

 

It's not about the consoles... it's just how the market is heading. The current-gen consoles triggered a string of unoptimization for reasons unknown. Like, before, devs had to squish memory down hard to make them fit on the last-gen consoles. So even if they wanted to be sloppy with the PC, we could usually brute-force it. But now they have oodles of memory and such, and they can fit in a lot more effects by still focusing on lower framerates.

 

The first sloppiness went straight into vRAM. "High resolution every texture ever! I don't care if it makes sense to have a 2048 x 2048 helmet texture as well as a 2048 x 2048 body texture! DO IT! AND MAKE THEM SHOES 4096 x 4096!" or something like that. Since that craze is over because they realized the whole world doesn't have 6GB and 8GB GPUs, and that high resolution textures doesn't make them look better/less muddy (just sharper), we've now encountered the "DEVOUR THE CPU! DEVOUR IT! WE'LL WAIT FOR DX12 AND UNTIL THEN WE'RE GONNA JUST EAT YOUR CPU FOR BREAKFAST!" stage. It sucks because unlike tossing high vRAM GPUs or more GPUs or whatever at the problem (which is a shitty way to deal with it), better CPUs don't exist when you already have a modern i7 that maxes near 100% load and can't even give 120fps in CoD BO3's beta on min graphics. Not that max graphics lowers the FPS any, because it's CPU limited >_>. Watch, I bet next we're gonna get RAM limited and everyone'll need 32GB instead of 8GB for recommended gaming.

 

Anyway. The reason for lack of SLI support is beyond me. Most of the new stuff nVidia are touting lacks SLI support (like MFAA) or has somewhat bad SLI support (like virtual reality) even though previous tech which was supposed to have the same limitations for multiGPU (like temporal filter AA) was circumvented by them (TXAA). A lot of new tech DOES require that AFR is not used, but I find it really stupid for things like Unreal Engine 4 to cut out SLI support AND REMOVE OTHER ADVANCED VISUAL TECH FROM ITSELF because "PCs wouldn't be strong enough to run it". It's like... you're cutting out the way to get the power, then complaining that nobody has the power. Explain.

 

TL;DR? I have no idea why SLI support is waning or sucking or people are utilizing it badly in games, but I don't think it's directly related to the consoles. I think they more just don't care anymore, and I can't say it's getting a lot of love from nVidia in the first place. I can't even consider AMD's option until it works in windowed mode either.

 

It's pretty crazy seeing manufacturers sport SLI or Crossfire but in real practice it isnt worth the headache. Maybe some enthusiast just like having more than one card just to make their rig impressive? I can definitely see why and it WOULD look awesome, but for a price? Not me at this point.

[D2ultima]

It's pretty crazy seeing manufacturers sport SLI or Crossfire but in real practice it isnt worth the headache. Maybe some enthusiast just like having more than one card just to make their rig impressive? I can definitely see why and it WOULD look awesome, but for a price? Not me at this point.

Around 2013 or so, it was more than feasible for many users to buy two midranged cards for cheaper or around the same price as one higher end card, and get a lot more power. But since lately that hasn't been going very well, it's not a surefire upgrade. When the downsides trump the upsides by a large enough margin, it becomes harder to recommend things. It is what it is.