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4k resolution, SLI 670s@16x pci-e2 or Tri-SLI 670s@8x?

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  • Resolution
  • SLI
  • Graphics
Last response: in Graphics & Displays
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September 25, 2013 7:57:54 PM

I'm newly upgraded to a 4k tv/monitor and having a bit of a question regarding the more optimal configuration. I'm running a EVGA x58 Classified 3 770 MB, and it supports Tri-SLI with 8x lanes. It can also run SLI with both at 16x. CPU is a i7-980, 24gb RAM. When I was running 3x1080p's@120hz I seemed to think it ran better as SLI, than TRI. I'm new to this much higher resolution and though I'd ask the crowd what they thought.

It also seems to only show 4gb of Vram in z-cpu, though each card has 2gb for a 6gb total. Thoughts?!

I currently have three gtx670's installed, but could pull one and ebay it if preferable. I'm not interested in jumping up to a new CPU/MB for the PCI-e 3.0, so gotta make due with what I have.


Thanks all for the thoughts!

More about : resolution sli 670s 16x pci tri sli 670s

September 25, 2013 10:19:33 PM

2Gb cards may have issues on a 4K resolution. Although, if you don't use max settings and no AA, you may be fine most the time. Take a look at this to get an idea, the 690 will have similar results as 670 2Gb SLI.
http://www.pcper.com/reviews/Graphics-Cards/Frame-Ratin...

You may wish to go with 3 or 4Gb cards. Remember, in multi-GPU configurations, your performance is still based on the amount of vram each card has on their own. You don't get to add up the Vram and use them as a single resource pool. Each card must load the same information as the next, so that each card can render the frame they are responsible for.
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September 26, 2013 6:48:42 AM

That's what I though regarding the Vram issue, so I guess the other 2gb is system reserved for the overhead? Seems I'll be shopping for 4gb Nvidia's.....wasted alot of money with ATI 7950's prior and won't return that side for awhile, unless they have markedly better 4k performance.

I don't run FPS or twitch games, more strategy or some mmorpg's, so crazy fps isn't the goal. The Seiki 39" I have will only push 30hz at 2160p, damned HDMI 1.4 limitation, no 2.0 yet and no displayport either. It does run 1080p@120hz though, for those games that run better that way ;) 

Still the main question remains, Is a gtx670 bottlenecked by a 8x Pci-E 2.0 pipe? Or would SLI at 16x/16x be preferable to Tri-Sli at 8x/8x/8x on a PCI-e 2.0 board?

My intuition seems to say the SLI route is the way to go, kinda found similar running Tri-3D or Tri-120hz at 1080p, but that video grade refresh rate does add in a different element. In Neverwinter for instance, even though the refresh is capped, I still get in the mid 40's with 3 cards. I think I'll pull the 3rd one this weekend and see for myself what the difference is on just the games I play, but the engineer in me is still wondering about the numbers of it all.

By no means am I displeased with the current setup, just a question of optimization and power consumption.
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September 30, 2013 6:44:55 AM

I did my own research over the weekend and indeed those cards are being bottlenecked severely by the x8 vs x16 lane at that resolution. To the degree that testing on 4 games with just the two in full speed was barely less performance than three at 8x. Until I can upgrade to a pcie-3 board, two will be the way to go forward. The 4gb is a necessity too at the resolution and maybe even at 1600p - certainly for triple monitor 1080p systems too and that would explain my previous errors in running that kind of display. So I'm ebaying the three gtx 670's and will take delivery of two new shiny 4gb gtx760's today and those should solve the new resolution problem as well.
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September 30, 2013 6:49:31 AM

You still have a 256bit bus with 760's, a couple of 780's would handle 4K much better, though are obviously far more expensive.
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September 30, 2013 6:58:05 AM

yeah, I noticed that as well, but I got the two 760's for less than the cost of one 780! We'll see if that bus is a bottleneck itself in the future, especially if I can get upgraded to a forthcoming 60hz 4k panel. Undiscovered country indeed!!!
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