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Discussion Starter · #1 ·
Hi, im in a dilemma here. I have an Asus Z87-K motherboard which has 1 PCIe 3.0/2.0 x16 (16x mode) and one PCIe 2.0 x16 (in x4 mode). Basically im wondering whether it would be worth getting another card and running it in SLI with the current card i have right now, since ive been looking around and it seems like the 4x mode wouldnt allow the graphics card to run at its best.

Advice would be appreciated.
 

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Quote:
Originally Posted by Xtremexx View Post

Hi, im in a dilemma here. I have an Asus Z87-K motherboard which has 1 PCIe 3.0/2.0 x16 (16x mode) and one PCIe 2.0 x16 (in x4 mode). Basically im wondering whether it would be worth getting another card and running it in SLI with the current card i have right now, since ive been looking around and it seems like the 4x mode wouldnt allow the graphics card to run at its best.

Advice would be appreciated.
Probably would not lose more than 10 to 20% FPS, if that much... based on my research into the same question.

Hard OCP testing: http://www.hardocp.com/article/2010/08/23/gtx_480_sli_pcie_bandwidth_perf_x16x16_vs_x8x8/#.UxoUdoVdt8s

This is an interesting article (older, but still pertinent... although cards have gotten faster since then, and need more bandwidth) ... http://www.tomshardware.com/reviews/pci-express-2.0,1915-11.html

Here is a thread on the same question: http://www.overclock.net/t/845107/performance-difference-between-pci-e-8x-8x-pci-e-16x-16x
 

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You can't SLI with the card in x4.
 

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Officially you can't. When I see threads like that I keep wondering if they used hacks (which are PITA), or once motherboard is SLI certified, it won't matter which PCI-E you use...
 

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Originally Posted by DeXel View Post

Officially you can't. When I see threads like that I keep wondering if they used hacks (which are PITA), or once motherboard is SLI certified, it won't matter which PCI-E you use...
Yea... I know what you mean. I cannot find anything "Nvidia official" that states it won't work. I did find this on Anand's site : http://www.anandtech.com/show/6934/choosing-a-gaming-cpu-single-multigpu-at-1440p

Quote from article above: "This is due to a not widely publicized requirement of SLI - it needs at least an x8 lane allocation in order to work (either PCIe 2.0 or 3.0). Anything less than this on any GPU and you will be denied in the software. "

Nothing here: http://www.geforce.com/hardware/technology/sli/faq

or here

http://www.nvidia.com/object/slizone_howtobuild_2.html
 

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OP... be careful! There may be a 8x minimum requirement that is not common knowledge. I don't even have a motherboard that has a PCIe 4x slot, or I would test it .
 

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Discussion Starter · #8 ·
Thanks for all your help. ill try and see if there is a minimum. if not ill try it. i can always just sell it i guess. or maybe in the summer buy a better motherboard (thought i would rather avoid that.)
 

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Quote:
Originally Posted by Xtremexx View Post

Thanks for all your help. ill try and see if there is a minimum. if not ill try it. i can always just sell it i guess. or maybe in the summer buy a better motherboard (thought i would rather avoid that.)
Will not work with out a hack.
I tried myself with two GTX 670 4gb on a Asus maximus Gene (one on top and one in the buttom black x4 slot to leave more room for air).
It was not detected :-/

For some reason x4 just isn't enough for Nvidia but is for AMD.

Another point to that, why isn't even PCI 3.0 X4 support?
It has the same bandwidth as a PCI 2.0 X8 which is supported
rolleyes.gif


Anyway, you will toss money at nothing unless you get another motherboard or go AMD
 

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Discussion Starter · #10 ·
Quote:
Originally Posted by Fruergaard View Post

Will not work with out a hack.
I tried myself with two GTX 670 4gb on a Asus maximus Gene (one on top and one in the buttom black x4 slot to leave more room for air).
It was not detected :-/

For some reason x4 just isn't enough for Nvidia but is for AMD.

Another point to that, why isn't even PCI 3.0 X4 support?
It has the same bandwidth as a PCI 2.0 X8 which is supported
rolleyes.gif


Anyway, you will toss money at nothing unless you get another motherboard or go AMD
if it wont work, then i might just focus on replacing my card with a 780 ti. also there are benchmarks of a 680 running in 4x. http://tpucdn.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/images/metro_2033_1920_1200.gif
 

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Quote:
Originally Posted by Xtremexx View Post

if it wont work, then i might just focus on replacing my card with a 780 ti. also there are benchmarks of a 680 running in 4x. http://tpucdn.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/images/metro_2033_1920_1200.gif
I doubt it, but perhaps Nvidia now allows for use of PCI-e 3.0 X4 in SLI.
But I would write an email to Nvidia and ask (they should know).

What you are linking to are a test of one GFX card in some different slot.
That is not a problem for Nvidia cards, but the PCI-e x4 limiting comes in play when running SLI :-/

Also I cant find your motherboard in here for SLI cable motherboards:
http://www.geforce.com/hardware/technology/sli/motherboards
 
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