Is it a bad idea to SLI sub cards of the same GPU type?

Araxie

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Like taking an RTX 2080 and SLIing it with an RTX 2080 Ti?
it can't be done.. for SLI both cards have to be the same Model.. RTX 2080Ti with RTX 280ti and RTX 2080 with RTX 2080 and so on..
 

Flybye

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it can't be done.. for SLI both cards have to be the same Model.. RTX 2080Ti with RTX 280ti and RTX 2080 with RTX 2080 and so on..
What about the various models of TI?
Like a TI FTW3 with a TI FTW3 Ultra?
 

Araxie

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What about the various models of TI?
Like a TI FTW3 with a TI FTW3 Ultra?
yup that can be done without issues.. in the past was recommended to link and sync memory clocks and core clocks of both cards but that's not an issue anymore.
 

defaultluser

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Alternate Frame Rendering requires the cards to be as close in performance as possible, if you don't want additional microstutter. And unfortunately, the AFR hack is the closest thing you will see to doubling video card performance.
 
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motqalden

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yup that can be done without issues.. in the past was recommended to link and sync memory clocks and core clocks of both cards but that's not an issue anymore.
Depends somewhat. While in general this is true, I have a 1080ti FTW3 and a 1080ti SC. The FTW3 sits about half an inch higher so good luck getting the SLI bridge to line up correctly.
 

JMCB

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As an owner of 2080 Ti SLI, I'd say avoid it like the plague (well, if you follow the modern day trend, you'll just end up getting it haha). But seriously, I have two cards, and the games that you don't need SLI you can run perfectly fine with one card, and the games that SLI would help hit that sweet 120FPS 4K spot don't support it. Just get one faster card (I plan on doing that for the 3080 Ti+).
 

Master_Pain

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As an owner of 2080 Ti SLI, I'd say avoid it like the plague (well, if you follow the modern day trend, you'll just end up getting it haha). But seriously, I have two cards, and the games that you don't need SLI you can run perfectly fine with one card, and the games that SLI would help hit that sweet 120FPS 4K spot don't support it. Just get one faster card (I plan on doing that for the 3080 Ti+).
This.

I have had a 4870x2 (2 cores in 1 card for you youngins), 2 x 7970s in Crossfire, and 2 x 780s in SLI. Support in games was always shit, even AAA titles. I believe AMD and Nvidia have both said on record that they aren't really doing any development on them anymore. Just put your money together and get the best card you can buy, or just 1 2080ti, and send the other $1300 to JMCB and me to split for saving you a headache.
 
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JMCB

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Yeah I've had 2x 4870s, 6970/6990 Trifire, 2x 7970s, 4x R9 290x Quadfire, 1080 Ti SLI, and now the 2080 SLI. I only got the second card because I found one for a steal of a price used locally (it was around $680 - it had a bad GPU fan that stopped working and the guy didn't want to bother with it - I just put it under water and it's been perfect). I don't think I'll ever do SLI/Crossfire again (unless, you know, I find another steal of a price secondhand lol).
 

Ricky T

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Like taking an RTX 2080 and SLIing it with an RTX 2080 Ti?
Just by the simple fact that you're asking that question means you really have no business fooling with SLI at all. You clearly have not even done any basic research at all on SLI so just go ahead and get that idea out of your head unless you want tons of aggravation. There really is no point in even discussing all the problems and potential issues here as this has been already discussed to death.
 

Flybye

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Just by the simple fact that you're asking that question means you really have no business fooling with SLI at all. You clearly have not even done any basic research at all on SLI so just go ahead and get that idea out of your head unless you want tons of aggravation. There really is no point in even discussing all the problems and potential issues here as this has been already discussed to death.
I have run SLI in games several times with different cards for 10+ years. Even with games that do not support SLI, Nvidia has a “force SLI” option in their control panel which has never let me down. I have never been dissatisfied with SLI, but I have never mismatched cards before. I always got the exact same model number as mine. But this time I ended up getting a Kingpin addition 980 Ti a while back, and their model numbers are somewhat rare. So I figured well would a 2nd 980 Ti of any variant work. I gave up after about 30 minutes of googling and not finding an answer of if different sub variants of a card would work with each other. My greatest apologies for aggravating your special specialness.

Problem is I need an analog output which new cards do not have. My cheapest and fastest option at the moment is another card of mine (980 Ti). I only originally mentioned a 2080 for an example. Anything under the Nvidia 2000 series is not worth the bump in performance from 1 980 Ti - based on different benchmarks I have seen. So replacing the 980 ti with a 1080 ti may not be worth it. Or a 1670. Only path that may be worth it is either SLI 980 Ti or a 2070/80series. But the 2000 series + the digital to analog adapter I need puts me in a price range I didn't want to spend on right now. A 2nd 980 ti should bump me up a decent amount for only a few hundred bucks which is a LOT cheaper than a 2070 or 2080 + cost of digital to analog adapter.
 

Furious_Styles

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I have run SLI in games several times with different cards for 10+ years. Even with games that do not support SLI, Nvidia has a “force SLI” option in their control panel which has never let me down. I have never been dissatisfied with SLI, but I have never mismatched cards before. I always got the exact same model number as mine. But this time I ended up getting a Kingpin addition 980 Ti a while back, and their model numbers are somewhat rare. So I figured well would a 2nd 980 Ti of any variant work. I gave up after about 30 minutes of googling and not finding an answer of if different sub variants of a card would work with each other. My greatest apologies for aggravating your special specialness.

Problem is I need an analog output which new cards do not have. My cheapest and fastest option at the moment is another card of mine (980 Ti). I only originally mentioned a 2080 for an example. Anything under the Nvidia 2000 series is not worth the bump in performance from 1 980 Ti - based on different benchmarks I have seen. So replacing the 980 ti with a 1080 ti may not be worth it. Or a 1670. Only path that may be worth it is either SLI 980 Ti or a 2070/80series. But the 2000 series + the digital to analog adapter I need puts me in a price range I didn't want to spend on right now. A 2nd 980 ti should bump me up a decent amount for only a few hundred bucks which is a LOT cheaper than a 2070 or 2080 + cost of digital to analog adapter.
This post was brought to you from fantasyland where SLI always works and never lets you down. Keep living the dream my friend.
 

Flybye

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This post was brought to you from fantasyland where SLI always works and never lets you down. Keep living the dream my friend.
I mean it always has for me when I have tried it. Maybe dual 980 Ti won't work for me this time so that I can come back and tell you that you were right so that you can feel all warm and fuzzy inside. It's not like I am claiming I have gotten double the performance in the past. It never has, but a used 2nd card is cheaper than buying a new single card that gave me the "same" performance as 2 sli cards. Hey you are more than welcome to add $ if I started a fund me event for a 2080.
 
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defaultluser

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The Cobra

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I was an SLI/Crossfire supporter for a long time. It used to be great back in the day. It has really fallen on hard times as most game developers haved moved to DX12 and don't even support mGPU even when the support is baked into the code. Rise of the Tomb Raider being one of the few games that actually support mGPU (DX12) and Ray tracing and had really good results. While the numbers were impressive, one game can't justify dual cards any more. I used to purchase dual cards all the time...BF4 being one when I ran a 295x2 and a R9 290x just because of the review from [H] at the time.
 

Flybye

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Last time I used SLI was with 2 x 660 Ti back in 2016/2017 when I switched to the 980 Ti.
I have a Sony CRT, so I am well aware of that thread, defaultluser ;-) Hence why I know the digital to analog converter is going to cost me $100+. :( This is why it's hard for me to get a better card due to the extra expense of the converter.

I am not saying I don't believe you guys. I'm just saying that I have been lucky in using SLI the last time I used it. Now I am curious to see just how broken everyone says SLI is lol. Thank you all. The 980 Ti isn't being too painful with what I play at the moment. Maybe I'll just stick with it until the 2080 gets cheaper after the 3000s roll out. Or maybe I'll pick up a cheap 980 Ti just to test how broken SLI is. I'll see. Thanks all for the input!
 

noko

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https://www.build-gaming-computers.com/sli-supported-games.html

How many here cracking their jaws actually have and curently using a SLI rig? Anyways above is a good list which if one was going to want to play several of those will be very much pleasantly surprised. Shadow Of The Tomb Raider using SLI was out of this world. FarCry5 as well. If you 4K game and the right games as in the ones you really want to play and would appreciate them, SLI is still an option.

What gets me are the whiners that want every game to run flawless with SLI, that has never occurred, even in the so called delusional hey days of SLI and CFX. Just can't sit still when one of the cards is not being used or having to turn off SLI to run a new game that, well already plays great with one card. Do I recommend SLI, yes, only to those who know what they are doing and understand the limitations of the technology. It was always a super enthusiast option, always had issues, always had many games that did not play well with it, will always have issues with when there are frame dependencies like in TAA, was always very costly which at times did not provide any benefit when used or even degraded the experience. Yet at times it would give you an experience you would have never had if you did not have it.
 

GotNoRice

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Back when I ran an i5- 2500K CPU, I ran 2x 4870x2 in Quad Crossfire. Then upgraded to 2x GTX680 in SLI. When I upgraded to my i7-5820K, that was during the height of the cryptocurrency boom that inflated GPU prices, so instead of getting a new card, I took advantage of the large number of PCIe lanes on the X99 chipset and got a 3rd GTX680. I used the 3x GTX680 cards up until last year when I upgraded to a 2080 RTX, and then when I upgraded to an AMD 3900X setup 6 months later, I put the 3x GTX680 cards back into my i7-5820k setup to use as my backup system.

For me, I can say that my experiences with 4-way Crossfire and 3-way SLI over the years have been largely positive. Part of that is because I've never been one to play dozens of games at the same time. I usually dedicate most of my time to a small handful of games, and thankfully over the years they have all had good SLI/Crossfire support.

When things changed for me was with DirectX 12, which pretty much killed SLI and Crossfire because of this fantasy idea that each game developer could write multi-GPU code directly into the game instead, and get better utilization than traditional SLI/Crossfire. In the real-world, pretty much no game developer actually bothers with this. SLI/Crossfire still works in many cases, but you have to run the game using DirectX 11, not 12. This is what I do when I run my backup 5820k system that still uses the 3x GTX680 cards. Those cards don't support DirectX12 in most games anyway, so it's not really much of a concession. I wouldn't want to be stuck having to use DirectX 11 with a new GPU though.
 

cybereality

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They need to be the same card, but I would add that SLI itself is not a great idea.

I've ran a few SLI rigs, and most recently had 2080 Ti SLI, but it ended up being not worth it.

Some games had huge gains, Tomb Raider in particular, but most games only had moderate improvement and some had glitches, stutter, or other problems.

However, a used 980 Ti is not that expensive. I see sold auctions for around $180, so for that money you might as well try and see for yourself.
 
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Flybye

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I will admit....you guys were right. You can't blame me for trying considering I had positive past experiences, though.

I used to be able to force SLI on almost any game, but now it is a complete disaster. I spent more hours than I will admit tweaking Nvidia profile inspector. At times I would actually see a gain of 50-60% fps increase, but what good did it do with so many artifacts. At least old games that were programmed to use SLI still took advantage of it. TAA has to be disabled since it also breaks with SLI. Even if it did work with TAA who knows what else would have to be disabled in the future to force it to work. Nvidia broke SLI so bad that even if I disabled SLI, I was still getting odd DX and driver crashing errors I didn't get before. Oh I so tried clean installing so many old drivers and even tried Nvidia's latest driver. The more I kept reading at how SLI has been thrown aside the more disgusted I got. Then I started reading up even more on DX12 and its lack of SLI support like some of you mentioned. I real shame since I have run multiple SLI setups in the past with no trouble. Guess I'll start reading up on NVLink, and I shouldn't be surprised there is a hopeful SLI successor.

Anyways, it looks like the 2070S will give me that bump in performance I think will be acceptable, so I will probably be going with that. I should be able to hold out for the 3000s to be released to hope the 2070 prices will go down. I already ordered the adapter I needed. :D
 

cybereality

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NVLink is basically SLI rebranded. It has some bandwidth improvements (maybe good for AI research or other compute tasks) but is no different for gaming over SLI.
 

noko

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NVLink is basically SLI rebranded. It has some bandwidth improvements (maybe good for AI research or other compute tasks) but is no different for gaming over SLI.
I wonder on the 3090 or 3080Ti if Nvidia will allow doubling up the ram when using NVLink for two cards?
 

The Cobra

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I wonder on the 3090 or 3080Ti if Nvidia will allow doubling up the ram when using NVLink for two cards?
They already do if the game supports DX12. I had a pair of 2080's in NVLink/SLI and Rise of Tomb Raider showed the pooled memory using DX12, SLI, DXR and DLSS before I sold them and went to a single 2080ti. DX11 has to be specially coded for pooled memory for example: Grand Theft Auto V. Otherwise, the second card's memory is not utilized, just the second GPU.

Also, NVLink (while basically SLI) is way more advanced and is really utilized in professional settings 3D rendering, Some Adobe products, Maya, et cetera...it offers massive amounts of bandwidth where AMD Crossfire uses the PCIe Bus and can constrain the bus.

NVLink/SLI/Crossfire while cool (and a feature I would use if more games supported it) just is not being coded for by the developers even though the support is already baked into the major game engines and DX12 Ultimate that most of the games use on their backend.
 
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noko

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They already do if the game supports DX12. I had a pair of 2080's in NVLink/SLI and Rise of Tomb Raider showed the pooled memory using DX12, SLI, DXR and DLSS before I sold them and went to a single 2080ti. DX11 has to be specially coded for pooled memory for example: Grand Theft Auto V. Otherwise, the second card's memory is not utilized, just the second GPU.

Also, NVLink (while basically SLI) is way more advanced and is really utilized in professional settings 3D rendering, Some Adobe products, Maya, et cetera...it offers massive amounts of bandwidth where AMD Crossfire uses the PCIe Bus and can constrain the bus.

NVLink/SLI/Crossfire while cool (and a feature I would use if more games supported it) just is not being coded for by the developers even though the support is already baked into the major game engines and DX12 Ultimate that most of the games use on their backend.
I was thinking more inline with Cuda/Compute oriented programs as in rendering. Will the gaming cards support that feature in the future? Now as for SLI or more exact mGPU, while I don't see that happening too much but twould be nice for some games to exploit that kind of potential.
 

The Cobra

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I was thinking more inline with Cuda/Compute oriented programs as in rendering. Will the gaming cards support that feature in the future? Now as for SLI or more exact mGPU, while I don't see that happening too much but twould be nice for some games to exploit that kind of potential.
They support it now, there would be no reason for them to remove it in the future. Lots of companies buy mid range gaming cards for work stations as a cheap solution in some studios that do graphics. I use Adobe After Effects and Premier CC and they both utilize NVLInk. I also know that Maya 3D supports SLI/NVLink. I got good render times on the 2080's using the Studio Drivers from Nvidia last year. You can also use the game drivers as well but you won't get the performance you would get from the Studio driver or an actual beefy Quadro card with the ODE Quadro driver.
 
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The Cobra

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I was thinking more inline with Cuda/Compute oriented programs as in rendering. Will the gaming cards support that feature in the future? Now as for SLI or more exact mGPU, while I don't see that happening too much but twould be nice for some games to exploit that kind of potential.
It was actually AMD who forced Nvidia to release a Studio Driver and support gaming cards for cuda loads in the first place since AMD pushes OpenCL. AMD released their professional driver for a lot of their gaming cards and flip between drivers for different things: Gaming vs Pro stuff with crossfire for both enabled if I wanted. I ran a pair of Vega Frontier Edition cards with the gaming drivers most of the time. They were a lot of fun but that is when I first started to see the performance losses in crossfire and overall multi-gpu glitchyness. That also shifted the market a bit and Nvidia was forced to respond in kind with the Studio driver.
 
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harmattan

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This.

I have had a 4870x2 (2 cores in 1 card for you youngins), 2 x 7970s in Crossfire, and 2 x 780s in SLI. Support in games was always shit, even AAA titles. I believe AMD and Nvidia have both said on record that they aren't really doing any development on them anymore. Just put your money together and get the best card you can buy, or just 1 2080ti, and send the other $1300 to JMCB and me to split for saving you a headache.
I don't know... I had an SLI and or Crossfire (or tri-SLI/Crossfire) setup every generation both nV and ATI/AMD since a set of 6800 GTs, both desktop and mobile. From the 7000 series to 295x2 support was relatively good, and worthwhile if you were playing at high resolution/IQ (albeit microstutter was always an issue). It used to be really the only way to get decent frames at 1440p and above. However, Since Vega and Pascal support has been miserable, and it's basically a non-entity now since current mGPU must be done software-level i.e. rarely.
 

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I don't know... I had an SLI and or Crossfire (or tri-SLI/Crossfire) setup every generation both nV and ATI/AMD since a set of 6800 GTs, both desktop and mobile. From the 7000 series to 295x2 support was relatively good, and worthwhile if you were playing at high resolution/IQ (albeit microstutter was always an issue). It used to be really the only way to get decent frames at 1440p and above. However, Since Vega and Pascal support has been miserable, and it's basically a non-entity now since current mGPU must be done software-level i.e. rarely.
Same. For me it all started with a DFI LANPARTY NF4 SLI board and a pair of 6800s in the mid 2000s. And since I had my FW900 since the mid 2000s as well, I wanted the extra power to be able to play at 2304x1440.
I fell a little behind the times not knowing about NVlink.
 

XoR_

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If SLI/CFX were using only SFR then lack of support would be saddening but SLI used AFR for most games and CFX used AFR exclusively... thus it is actually good they dropped support for this technologies.
 
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