SLI scaling with 780 Ti

[Manoa]

I have 2 780 Ti's running SLI (very well) but they have some difficulty in heavy games for example killing floor 2 gives 37 fps (3840x2160)
I already have an another 780 Ti one that should be compatible with the existing ones
but I don't have an another x16 slot on the mobo (but I have an idea on how to "mount" the card)
what I am asking and wanne do is use a riser from x1 to x16 to connect to the card from the x1 connector
is sutch a thing is possible ?
but more important: is it recommened ? will it give significantly more performance over 2 cards ? or games don't realy give much above 2 ? will 3 cards increase significantly response time ?
I have the power and cooling (my radiator is at his limits during summer so I could buy another radiator if this works)

 

[BadFrog]

What motherboard are you running

Running x8 x8 instead of x16 x16 won’t makr a difference in performance.

Scaling to 3 cards over 2 for gaming doesn’t work well. Suggestion is to sell all your cards and buy a 10 or 20 series single gpu

 

[Toothless]

Unless you got the 6GB cards, you might as well sell the 780Ti's and get something newer.

 

[agent_x007]

What game and other settings ?
With SLI of 780 Ti, you might get out of VRAM quite easily with 3GB VRAM.

@Toothless There are no 6GB 780 Ti (unless you count the not released MSI ones).
You need TItan Black's for 6GB with 780 Ti performance.

 

[Manoa]

it the asrock Z87 extreme 3
killing floor 2 with flex and custom INI graphics settings and reshade - 3840x2160 - it's 37 fps with the 2 cards SLI
race driver GRID HD special custom edition with many many mods and custom reshade, using TOCA3 SLI code - 95 fps 1920x1080 2 cards
need for speed underground with 2 texture mods and custom reshade - 3840x2160 20 fps (single card, SLI don't work), 1920x1080 60 fps (limit of game)
doom 3 many many heavy mods 3840x2160 - 50 fps but when plasma gun firing it's down to 30
need for speed shift 2 3840x2160 - between 50-60 fps, single card (still working on SLI for this game)
left 4 dead 1 with custom reshade 3840x2160 - 40-60 fps
left 4 dead 2 with custom reshade 3840x2160 - 37 fps

monitor gives 120 hz
resolution is DSR, the monitor is a 1920x1080
I can't buy the 10 or the 20 cards, they too expencive, just to get the performance of 2 780 Ti SLI I need 1080 Ti which alone cost 1000$ (zotac AMP extreme), and that just to get the same performance I already have, and picked a very bad time to advice buying cards :x
yes video memory can sometime be a problem but the driver allow me 16 giga from system memory to use as video memory so far I didn't see any drop in performance when doom 3 allocated over 3 giga video memory with 150 MB tga per texture, I think it becouse I have faster system memory (2400 mhz DDR3 10-10-10-31, I tested it and it gives ~24 giga speed)

 

[Mescalamba]

Second hand 1080 Ti doesnt cost much, neither do Vega 64. Buying them new doesnt make sense.

2070 is pretty able too.

Also there is actually question of CPU. While it shouldnt bottleneck at 4K, it still might hamper performance. Like in my case, I need to upgrade whole system, cause even if I got 1080 Ti it would underperform rather badly.

 

[Manoa]

lel man the cheepest 1080 ti in ebay is costing 600+$ and it second hand !
leave yourself from this !

 

[BadFrog]

I can't buy the 10 or the 20 cards, they too expencive, just to get the performance of 2 780 Ti SLI I need 1080 Ti which alone cost 1000$ (zotac AMP extreme)

No way sli 780 ti and a single 1080 ti is equal in performance

 

[cdawall]

No way sli 780 ti and a single 1080 ti is equal in performance

Two 1070's equals a 1080ti...pair of 780tis is going to be closer to a single 1070 than a 1080ti

 

[Manoa]

ok but still 600$ ? mybe some other time when it's not 600$ lel
but beside this, do you think this PCIE riser idea will work ? will it be worth and work good ?
buying cards anybody knows

 

[BadFrog]

ok but still 600$ ? mybe some other time when it's not 600$ lel
but beside this, do you think this PCIE riser idea will work ? will it be worth and work good ?
buying cards anybody knows

Sell your 3 780 ti’s on eBay. They are selling for 100 bucks each. That’s 300. Now u only need to spend 300 for your card.

 

[Manoa]

lel man money realy have no value to you ? riser on ebay is costing 2$ with shipping
actually now that you mention it 100$ mybe I should buy another 780 Ti to do SLI with 4 ....

 

[BadFrog]

What monitor do you have?

 

[Toothless]

@Toothless There are no 6GB 780 Ti (unless you count the not released MSI ones).
You need TItan Black's for 6GB with 780 Ti performance.

I was thinking of the 780 6GB.

 

[Vayra86]

lel man money realy have no value to you ? riser on ebay is costing 2$ with shipping
actually now that you mention it 100$ mybe I should buy another 780 Ti to do SLI with 4 ....

You can do whatever you want, but...

- SLI scaling at more than 2 cards is *horrible*
- SLI support in games is drastically reduced compared to 3-4-5 years ago, and it is not getting better. DX12+Vulkan makes it even worse. There are more APIs to support, and less cards that even have SLI fingers (most don't these days!). The market to optimize for SLI is dwindling fast.
- Power draw of 3x780ti (650-700w worth of power draw) is also costing you money, and the perf/watt on 3 badly scaling cards is easily going to be 40-80 dollars/year wasted depending on how much you game - even versus just two cards. I don't know how long you've been running this, but you can safely say you're wasting 60-90 dollars per year on SLI as a whole compared to having a recent, energy efficient card instead. Here's the kicker: 2014 ~ 2018 was costing you about 300 dollars extra that you are lacking now to buy the card you need.
- You have a 3GB VRAM problem and 3 or 4 cards will not fix that, they will actually make it worse. Now you don't just have lack of VRAM, you also have more overhead.
- Even a single 780ti is already obsolete at this performance requirement. You are running 4K. You need at the very least a 4GB VRAM card. And that's for medium, 60 fps 4K on 2016 titles. I won't even start about 2018 and newer, given your examples, and let's just not even mention high or ultra, things may catch fire.
- Kepler Refresh (7xx) cards do not have delta compression or any other aids to decrease load on the memory bus.

Bottom line, sell the cards, get something decent instead, and drop your SLI illusions. Its shit, the technology is rapidly going End Of Life, get with the program. The alternative is you troll this topic with saying you'll buy another one for five-way SLI and get nowhere. You've asked for advice, take it. Single card is the way to go. I can bet you right now even my single GTX 1080 can run circles around your 3x780ti any day of the week... and I came from a single 780ti Games these days NEED VRAM. Badly. And at 4K, doubly so. I can fill up 4-5 GB on 1080p, go figure.

Even a single 980ti would be worth going for btw, if money is a problem. You'll get 2x the VRAM. But preferably, find a 1070ti or a 1080 (or better, don't get RTX 2060 though as it has just 6GB and is too expensive for that/your spec).

Oh and by the way, if you need proof - versus a measly GTX 1080: equal FPS at 1080p, horrible performance at 4K, do watch the whole video.

Don't forget the 1080 needs 200w at the most, 2x780ti needs 400-450w.

Sell your 3 780 ti’s on eBay. They are selling for 100 bucks each. That’s 300. Now u only need to spend 300 for your card.

Exactly, and every day you wait, that price can drop like a stone as Turing cards become more readily available and the 350 dollar price point is fought over, while Nvidia is readying lower end 150~250 dollar cards as we speak. These 780ti's are about to go completely worthless.

 

[dorsetknob]

Not to sure but
running 2 780 Ti's running SLI (8x+8x) and then adding 1 a 3rd (1x)
cards then run at lowest performance level = 1x+1x+1x
seems like you get a very big performance hit

ps not ever run SLI so forgive me if i'm wrong.
like others have suggested
sell your current Cards and buy ONE that is Capable

edit seem to remember SLI requires min of 8x so adding one at 1x it wont work ?

 

[Mescalamba]

Not to sure but
running 2 780 Ti's running SLI (8x+8x) and then adding 1 a 3rd (1x)
cards then run at lowest performance level = 1x+1x+1x
seems like you get a very big performance hit

ps not ever run SLI so forgive me if i'm wrong.
like others have suggested
sell your current Cards and buy ONE that is Capable

edit seem to remember SLI requires min of 8x so adding one at 1x it wont work ?

No it wont work and mostly I wouldnt even bother with it unless I had x16 with two lines. Means some pretty high end PC.

SLi works tho and rather reasonably ok, if you play most "mainstream" games. In the future, there is chance it will work even better (at least in DX12). But we not there yet.

 

[Vayra86]

there is chance it will work even better (at least in DX12). But we not there yet.

A snowballs' chance in hell Devs need to implement it themselves. At this point DX12 adoption rate for developers is quite low and/or the implementation is bad. It will take years before DX12 gets enough market share to even begin thinking of mGPU support. But it all begins with hardware regardless, and if the midrange is out of the game, you can safely forget about it.

 

[EarthDog]

I think you are wasting your time here going SLI with that CPU setup anyway. Not only are you losing 1-2 % running x8/x8 (normal), but that CPU will hold FPS back at 1080p. x1 slot will neuter the cards and performance.

This is, all around, a bad idea.

 

[cucker tarlson]

Kepler cards are ancient,you got two 250W cards that are gonna lose to a single 2060 and think of adding a third ?



get a 1070ti/Vega 56

 

[kastriot]

Sell them and get rtx 2060 if you want 60fps 4K in KF2 (flexff, RR-ff, AOff), have a nice day!

 

[cucker tarlson]

Sell them and get rtx 2060 if you want 60fps 4K in KF2 (flexff, RR-ff, AOff), have a nice day!

6gb for 4k is not a good idea. 1070ti/v56 is what he should aim for.

 

[EarthDog]

Whiiiiiiiiiiiiiiiiiiiiich can't really play 4K well at all without major IQ sacrifices...

 

[cucker tarlson]

but it's the best he can get with a reasonable budget. 1080ti/2080 would do 4k/60 with little to no settings tweaking but they cost much more.

 

[EarthDog]

Ok...that still doesn't change the fact that a 1070Ti or V56 are not 4K UHD cards. His budget is not my issue. I was simply replying about performance of those cards at the resolution. If he cannot/does not want to afford a proper card for the res, that is on him.