Wouldn't 980 Ti SLI be bottlenecked by PCIE 3.0 x8 on 115x?

Magic Carpet

Diamond Member
Oct 2, 2011
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I know the regular 980 was, at least in this game. And 980 Ti is even more powerful. So what happens when you game with two of these in SLI on a mainstream 115x system with limited pci-e b/w (8 lanes for each card)? Surprised nobody has come up with a comparable test yet. Discuss!

Hint: suing Intel isn't an option :)
 
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RussianSensation

Elite Member
Sep 5, 2003
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ryse_1920_1080.gif


I know the regular 980 was, at least in this game. And 980 Ti is even more powerful. So what happens when you game with two of these in SLI on a mainstream 115x system with limited pci-e b/w (8 lanes for each card)? Surprised nobody has come up with a comparable test yet. Discuss!

Hint: suing Intel isn't an option :)

Intel? Intel provides sufficient lanes on their X99 motherboards or even Z170. The bottlenecking will be almost non-existent.

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If you have 980Ti SLI, and you are running 1080P/1200P, you will be CPU limited MUCH more than PCIe limited. If you are running 1440P/4K, you will be GPU limited MUCH more than PCIe limited.

Usually when people switch platforms from an older gen i5/i7, they start assuming they were PCIe bottlenecked when the huge performance boost they are seeing is coming from a higher IPC and much faster CPU architecture, not PCIe lanes. Overall, 3-4% isn't a bottleneck. If you want to get math picky, an upgrade from i7 4790K to 6700K OC would provide a greater boost in minimum fps than moving from PCIe 2.0 x8/x8 SLI to 3.0 x16/x16. Micro-stuttering, SLI/scaling profiles, and enough CPU speed at lower resolutions or enough GPU horsepower at higher resolutions is the big factor.
 
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Techhog

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Sep 11, 2013
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Ryse is the exception that proves the rule. It stands out specifically because no other game is bottlenecked like that.
 

moonbogg

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Jan 8, 2011
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I actually tested this (sort of) when I realized my board was running at PCI x8 3.0 speeds. I fixed it to run at x16 and retested some stuff and...and...I don't even remember what happened. Nothing basically. Or maybe something happened, but I would have to go back and look. It wasn't a big deal whatever it was.
Actually my 3D mark score went up but I forgot by how much. Oh hell this post was lame. Sorry.
 
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RussianSensation

Elite Member
Sep 5, 2003
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Ryse is the exception that proves the rule. It stands out specifically because no other game is bottlenecked like that.

Maybe in his previous testing it was a motherboard/chipset driver issue. Ryse doesn't change anything.

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At least on the Fury X, Ryse is CPU and heavily GPU limited, not PCIe 2.0 x8/x8 limited. Another possibility that I will admit I didn't consider earlier in this thread is that NV's Maxwell 980/980Ti could be more PCIe limited in some games that AMD's Fiji products do not suffer from. Overall, I would say the primary upgrade from PCIe 2.0 x8/x8 platforms is the faster CPU architecture, support for NVMe M.2 PCIe drives, and the option of going 6-8 (or possibly 10 cores) with X99.
 
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Magic Carpet

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Oct 2, 2011
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Appreciate all the replies, thanks. Yeah, it looks like we aren't there yet. TPU is planning to do a similar test with Maxwell SKUs in SLI, pretty soon. Will have more information.
 

RussianSensation

Elite Member
Sep 5, 2003
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Appreciate all the replies, thanks. Yeah, it looks like we aren't there yet. TPU is planning to do a similar test with Maxwell SKUs in SLI, pretty soon. Will have more information.

:thumbsup: Ya that would be very helpful because it's possible that Fury X and 980Ti may respond differently to PCIe bandwidth bottlenecks. Having said that, are you really considering going 980Ti SLI at this point? I would have imagined that a single 980Ti OC is plenty fast for 1440P and below unless you are on a 100-144hz 1440P screen?