To SLI or Not to SLI, that is the question - Thoughts Needed

[GreiverBlade]

1. Performance boost guaranteed
2. More VRAM with 2 cards than a single one.

1. no
2. no

1. Not all games support it ( for example, BF3 and BF4 on my 2 6770HD works awesome, 1080p with ultra textures, no effects, 60fps average). It depends on the game with what GPU manufacturer is it ment to be played.
2. Higher temps and more noise from fans.

1. yes
2. yes

funny ... you pinpointed correctly the drawbacks, but missed totally the advantages (both of the one you state are wrong, well for more performance it's more a "maybe" than a "guaranteed" )

if you duplicate, then logically both cards will have same usage and same temps.e.

and again no, the one on the top will always be hotter since less airflow due to the constrain of the SLI/CFX positioning, in my GTX 580 SLI temps where higher for the master (around 15-20°C more) and lower for the slave, then performance boost? not really here or noticeable, at least not 100% of the time maybe 40-60% instead. your usage only indicate a bottleneck somewhere

The second card is here to help the first with boost and vram for things the main card can't process at higher settings..

not totally wrong but not totally true, each card alternate a frame so they need to have the same data duplicated between the 2 GPU and vRAM

Edit: Also you would need 2 HDMI for 1 monitor or 2 monitors to play at CFX or SLI Mode if data is duplicating to both cards.And by duplicating you cannot get boost because both will render same stuff and it will make no difference if you play with single card or dual cards, by duplicating, performance will be the same.

well ... again ... no.
for the alternate render: look above
the SLI/CFX bridge is here for that (or the bridgeless xDMA frome the 290 and after ) does the job for the exchange of the data between of the master and slave.

 

[64K]

It cannot be duplicated.
The usage on both cards is not the same.
Main goes 90% while second does 60 to 70%.
GTA 5 for me with 1 card shows 1 GB, but when I apply CFX, it shows 2GB in graphics settings.
Also a proof are the temps on my cards.
Main get to 85C while second hits 60C.
If you duplicate, then logically both cards will have same usage and same temps.
The second card is here to help the first with boost and vram for things the main card can't process at higher settings.

Edit: Also you would need 2 HDMI for 1 monitor or 2 monitors to play at CFX or SLI Mode if data is duplicating to both cards.And by duplicating you cannot get boost because both will render same stuff and it will make no difference if you play with single card or dual cards, by duplicating, performance will be the same.

Here's a good read if you want to know more about SLI

http://www.geforce.com/whats-new/guides/introduction-to-sli-technology-guide#1

AFR (Alternate Frame Rendering) has been used to get the most performance with SLI in the past but DX12 may change that with Split Frame Rendering (if it works).


Alternate Frame Rendering (AFR)

"Alternate Frame Rendering is the performance rendering mode for SLI, and it works by designating a particular frame subset to each GPU. In a 2-way SLI configuration, for example, GPU 1 would render all odd-numbered frames while GPU 2 renders all of the even-numbered frames. When using three or four GPUs, the GPUs render one of every three or four frames respectively. The essential principle behind AFR is keeping the GPUs working as independently as possible for maximum performance gains, and that takes a well-defined SLI rendering profile. These are being written and optimized for many different titles all the time, so check for new GeForce drivers often! If you would like to submit a request for an SLI profile update for a game or 3D application, click here."


SFR supposedly works by having GPU 1 render the top half of a frame and GPU 2 render the bottom half of the same frame. In which case you would gain some VRAM overall per rendered frame by having two cards but bear in mind you would still need textures in both frame buffers so it wouldn't double the VRAM available for rendering a single frame by having two cards. (If it works)

 

[...PACMAN...]

Thanks for that 64k, I shall have a read later

 

[...PACMAN...]

Guess what just arrived PALiT GTX 960 JetStream 4GB Number 2!!

Can't take a picture as my phone is bust and the GF is away at the parents for the weekend. I'll be creating a benchmark thread either tonight or early tomorrow to share my findings. Would be great if you could join me.

This will be the first time I potentially have performance of a top tier card

THIS IS GONNA BE SO MUCH FLIPPING FUN

 

[...PACMAN...]

The right said thread has been created here ----->
(1st Time SLI User) SLI GTX 960 PALiT JetStream 4GB - Benchmarks & Thoughts

 

[D007]

I'd rather have one Titan Z than two 980's.. Less issues with compatibility and sli drivers.
Been using sli for a long time. My 2 cents. with a game that properly utilizes sli though, it's beast..

 

[R00kie]

I'd rather have one Titan Z than two 980's.. Less issues with compatibility and sli drivers.
Been using sli for a long time. My 2 cents. with a game that properly utilizes sli though, it's beast..

Erm... What?
Those are both dual GPU solutions.

 

[neatfeatguy]

I am officially on my first single GPU gaming build. I've always ran SLI (because I could....? I'm not entirely sure, but I did like it). I ran the following cards in SLI over the past 10-11 years with very little issues:
7600 GT PCI-E
8800 GTS 640MB (G80 chip)
8800 GTS 512MB (G92 chip - blew my mind how powerful these were compared to the G80 chip) - I used EVGA Step-Up to go from the 640MB versions
GTX 280s (one was sent back for RMA - got a GTX 285 as replacement. the 285 was faulty, but BFG closed doors and I couldn't return it. I flashed it with a 280 BIOS and it worked like a charm. Ran the flashed 285 and 280 in SLI as 280s)
GTX 570s

I've had very few issues with SLI outside of the normal extra power draw and heat. The driver 182.50 was the most stable driver for almost a 7 months for the 8800 GTS 512MB cards I had. A few games I've come across do not support SLI and a few games ran very poorly with SLI enabled. Disabling SLI only takes a few moments and then I'd be gaming without any issues.

The main reason I did SLI (other than I could) was because I generally moved to newer cards once they were a generation old already and I could get two of higher-end cards for the same cost as the high-end flagship card. I got two 570s for around $550 when the 580 was still going for about $500. I get good single card power should SLI not be supported in a game or I'd have greater performance over a single 580.

I'd only recommend SLI for people that want the best of the best and to only SLI high-end cards. Running mid or low end cards in SLI isn't worth it since they generally don't provide the same performance as a single high end card. Also, if you run into games that have no or poor SLI support, you're left with a mediocre single card running the game.

I'm running a Zotac GTX 980Ti AMP! Omega that just tears through games and for the first time in a decade, I won't be doing SLI.

If you do run SLI and you won't be using water cooling, the top GPU will always run hotter - generally 10C hotter, especially on the more demanding games. Hopefully you have a decent tower with enough cooling and hopefully your MB gives ample space between the two cards so they're not hugging when installed, otherwise you're really going to choke the top card.

 

[D007]

Erm... What?
Those are both dual GPU solutions.

No, it's not... lol

I said I would rather have one titan than two 980's....

Even then you can always buy another titan later if you want.
At least you have the top of the line though, with one card, that is more reliable than two.

 

[manofthem]

I'd rather have one Titan Z than two 980's.. Less issues with compatibility and sli drivers.
Been using sli for a long time. My 2 cents. with a game that properly utilizes sli though, it's beast..

Erm... What?
Those are both dual GPU solutions.

No, it's not... lol

I said I would rather have one titan than two 980's....

Even then you can always buy another titan later if you want.
At least you have the top of the line though, with one card, that is more reliable than two.

Correction here. What he meant is that a Titan Z is a dual gpu setup, 2 gpus on single card. From Nvidia's site:

ULTIMATE POWER. THE NEW GEFORCE® GTX TITAN Z.
GeForce® GTX TITAN Z is a gaming monster, the fastest card we’ve ever built to power the most extreme PC gaming rigs on the planet. Stacked with 5760 cores and 12 GB of memory, this dual GPU gives you the power to drive even the most insane multi-monitor displays and 4K hyper PC machines.

@gdallsk was indeed correct, both are dual gpu setups

 

[D007]

Correction here. What he meant is that a Titan Z is a dual gpu setup, 2 gpus on single card. From Nvidia's site:


@gdallsk was indeed correct, both are dual gpu setups

No, he's not...

Do you have to enable sli for it to work? No, then it's one card..
Idc if it's 50 bajillion cards on one plate.. It is one card and the system reads it as one card.
The point being and I thought this was clear. Using SLI can be trouble.. The titan Z is not using sli, it is one card..
I hope we cleared that up..

Just in case, to clarify..
Single card Titan Z. No sli required:

Two Titan Z.. Sli required:

We good? Ok. I mean not like I don't have the highest sli scores in benchmarks for the 980's on this site, for both valley and haven.. Not like I have any idea what I'm talking about.
Not like I haven't been using sli since it was first introduced..lol
Just sayin..
Seems like you're debating for the sake of debating.

 

[Shibumi]

No, he's not...

Do you have to enable sli for it to work? No, then it's one card..
Idc if it's 50 bajillion cards on one plate.. It is one card and the system reads it as one card.
The point being and I thought this was clear. Using SLI can be trouble.. The titan Z is not using sli, it is one card..
I hope we cleared that up..

Just in case, to clarify..
Single card Titan Z. No sli required:
View attachment 69901


Two Titan Z.. Sli required:

View attachment 69902

We good? Ok. I mean not like I don't have the highest sli scores in benchmarks for the 980's on this site, for both valley and haven.. Not like I have any idea what I'm talking about.
Not like I haven't been using sli since it was first introduced..lol
Just sayin..
Seems like you're debating for the sake of debating.

Wow, you're really confident for someone who has no idea what they're talking about. A Titan Z is a dual gpu on a single card. Even you though you don't have to enable sli for it to work, you still have all the limitations of a sli setup.

 

[Filip Georgievski]

Limitation and f.....g pissed off for not every game working properly.
I mean I'm using CFX and for some games I'm glad it works. But for most titles that I want to play it f...s it up.
Single card is way better than SLI or CFX in any day, night, dawn or noon.
Single 980TI or R9 390X dominate in gaming.

 

[manofthem]

No, he's not...

Do you have to enable sli for it to work? No, then it's one card..
Idc if it's 50 bajillion cards on one plate.. It is one card and the system reads it as one card.
The point being and I thought this was clear. Using SLI can be trouble.. The titan Z is not using sli, it is one card..
I hope we cleared that up..

Just in case, to clarify..
Single card Titan Z. No sli required:
View attachment 69901


Two Titan Z.. Sli required:

View attachment 69902

We good? Ok. I mean not like I don't have the highest sli scores in benchmarks for the 980's on this site, for both valley and haven.. Not like I have any idea what I'm talking about.
Not like I haven't been using sli since it was first introduced..lol
Just sayin..

Nvidia calls the card a "dual gpu" on their own site. Whatever bro

Seems like you're debating for the sake of debating.

Hardly. I'm not known to do that.

 

[trog100]

the nvidia sli solution has far more driver support than the crossfire solution..

the top card of the two will always run hotter.. its not reduced air clearance its simply because the top card is pulling warm air in which is already heated up by the bottom card..

sli works fine for me.. my two 970 cards worked fine.. the top card ran about 7 C hotter than the bottom card.. my two 980 ti cards work fine in sli with the top card running about 15 C hotter than the bottom card.. cranking up the fan profiles gets this down to about 10 C difference.. heat is a problem with a pair of 980 ti cards.. mine now run at 60 C bottom and 70 C top..

the bottom card heats up the top card and both cards together heat up the air the cpu cooler gets.. that is with a noctua 2000 rpm industrial fan blowing directly in from a side case fan..

even with the case side off you can feel (with your hand) the hot pocket of air above the two graphics cards.. the snag is the cpu cooler pulls in this hot air.. i recon the two room heater type cards add about 20 C on the cpu temps when they are both working hard....

just running wrpime i see a cpu temp of 58 C.. running wprime and the heaven benchmark tool at the same time i see close to 80 C.. the extra 20 C is heat coming off the graphics cards.. that is with an undervolted cpu clock of 4.2 gig.. running at 4.6 gig adds another 20 C.. he he..

i now have two options.. spend a fortune on a new (full size) case and full water cooling or settle for a clock speed of 4.2 gig..

trog

 

[64K]

The Titan Z it is two GK110 chips on one card (dual GPU).
You don't enable SLI because it's automatically enabled but it is running in SLI mode and uses SLI driver profiles where they are available.

The only difference (according to Nvidia)

"Unlike traditional dual-GPU cards, Titan Z’s twin GPUs are tuned to run at the same clock speed, and with dynamic power balancing. So neither GPU creates a performance bottleneck."

http://blogs.nvidia.com/blog/2014/03/25/titan-z/

 

[newtekie1]

No, he's not...

Yes he is.

Do you have to enable sli for it to work? No, then it's one card..

Actually, with the Titan Z, you do have to enable SLI for it to work. With a single Titan Z installed in the system, the SLI option appears in nVidia control panel and you have the option to enable or disable it. If you leave it disabled the 2nd GPU won't be used. The only difference is that the option is enabled by default with the driver detects a Titan Z.

Idc if it's 50 bajillion cards on one plate.. It is one card and the system reads it as one card.

The card shows up as two cards to the system. The PCB uses a standard PLX bridge chip, same thing you'd find on a lot of motherboards to split 16 lanes from the CPU into 32 to provide two full x16 slots on 115X motherboards. In this case it takes the 16 lanes from the slot it is plugged into, and splits it into two 16 lanes for each GPU.

The SLI bridge that would normally be external on single GPU cards is on the PCB here, with one SLI bridge being routed to an external connection for quad-SLI.

It has been this way for all the dual-GPU video cards from nVidia since they went to the single PCB design.

The point being and I thought this was clear. Using SLI can be trouble.. The titan Z is not using sli, it is one card..

It is using SLI, and subject to the same problems as any other dual-GPU setup.

Do you really think nVidia designed some magical new system that works perfectly all the time just for the TitanZ?

 

[GhostRyder]

No, he's not...

Do you have to enable sli for it to work? No, then it's one card..
Idc if it's 50 bajillion cards on one plate.. It is one card and the system reads it as one card.
The point being and I thought this was clear. Using SLI can be trouble.. The titan Z is not using sli, it is one card..
I hope we cleared that up..

Just in case, to clarify..
Single card Titan Z. No sli required:
View attachment 69901


Two Titan Z.. Sli required:

View attachment 69902

We good? Ok. I mean not like I don't have the highest sli scores in benchmarks for the 980's on this site, for both valley and haven.. Not like I have any idea what I'm talking about.
Not like I haven't been using sli since it was first introduced..lol
Just sayin..
Seems like you're debating for the sake of debating.

Titan Z is a dual GPU card, even with it on one slot its registered as SLI in the settings. Its been like that since the beginning (I have had a single and pair of GTX 295 cards, 9800X2's, HD 6990's, etc) with both sides as when you plug them in you have to enable SLI/CFX to use both GPU's on the cards (Well all mine except the 9800's seemed to start SLI/CFX automatically).

 

[The N]

Titan Z is no doubt a Dual GPU, 2x Chip on PCB. 295x2 is another example of Dual GPU in a single slot.

 

[MxPhenom 216]

No, he's not...

Do you have to enable sli for it to work? No, then it's one card..
Idc if it's 50 bajillion cards on one plate.. It is one card and the system reads it as one card.
The point being and I thought this was clear. Using SLI can be trouble.. The titan Z is not using sli, it is one card..
I hope we cleared that up..

Just in case, to clarify..
Single card Titan Z. No sli required:
View attachment 69901


Two Titan Z.. Sli required:

View attachment 69902

We good? Ok. I mean not like I don't have the highest sli scores in benchmarks for the 980's on this site, for both valley and haven.. Not like I have any idea what I'm talking about.
Not like I haven't been using sli since it was first introduced..lol
Just sayin..
Seems like you're debating for the sake of debating.

A Titan Z is SLI on a stick. It is two GPUs on one card that uses a small bridge chip to allow the GPUs to communicate, rather than the tradition ribbon bridge connector. Its SLI whether its 2 seperate cards, or one card with 2 GPUs on the same PCB. If you use two TITAN Z then its quad SLI.

 

[trog100]

totally off topic this but just something interesting i have noticed..

i bought a second (identical) ribbon cable to fit on my two 980 ti cards.. as much just to look "good" as anything else..

with two ribbon cables fitted i get a strange flickering banding effect across the entire monitor screen.. one cable must somehow interfere with the other.. basically even though it seems like a good idea it dosnt work.. he he

trog

 

[PP Mguire]

Oddly enough my setup doesn't go with traditional SLI occurrences. My bottom card is recognized as GPU 0 and is heated up more although technically both should be identical as cooling for both is the same (from front of the case). Same scenario when using air cooling as the bottom card was against the PSU cover plate and was about 5c hotter than the top card.

 

[trog100]

my tuning software seems to swap the card numbers around.. if i just run one the software calls it number 1 and its always the top card..

if i run two cards number 1 is the bottom card and the top card is number 2.. its easy for me to tell which card is which.. but the numbers have confused me..

i think if the software fully uses both cards the load on them is about the same.. i mostly game on just the one card and would like to be able to swap them around but dont seem able to.. furmark shows the difference between the cards quite well..

this is with the fan profile set to run flat out at 65 C.. done to keep the bottom as cool as it can be because its backplate temperature directly affects the top cards temperature..

a 20 C difference in temps with both cards doing roughly the same work..

trog