No Sli option in Nvidia. Possibly Pci x16/x8 issue?

First of all I apologise in advance for my sheer stupidity.

My system:
Proc:- i7 3770k 3.5Ghz @ 4.5Ghz
mobo:- Gigabyte GA-Z77X-UP4TH
Cards:- 2x 680 GTX (KFA2 both exactly the same version) "sli"

I have scoured the interwebs for help with my sli issue. Both cards are detected in device manager as working without any alerts for any issues. Both are being detected on the nvidia control panel however there is no option for sli. Where the sli configurator option should be there is the option "Configure Surround, PhysX".

I have tested each card indiviudally and both are in full working order. I have uninstalled and reinstalled the drivers during this process for each to rule anything out. Also I have tested several different SLI bridges in all configurations.

I have an Asus sound card in the lower slot which I don't believe should affect anything.

The system was built by overclockers UK and as much as I value their skills I can't help but think maybe there is something that was overlooked their end as I have made no changes (as yet) to my system.

On looking at GPU-z I can see the Bus Interface is different for both cards. They are as follows:

Card 1 - PCI-E 3.0x16@x8 1.1
Card 2 - PCI-E 3.0x16@x4 1.1

As far as I can figure out, this is my issue right here however my knowledge is completely lacking in changing these speeds.

Any guidance would be very much appreciated and can it be confirmed that I have diagnosed the issue correctly?

Many thanks in advance for any thoughts over this.
2 answers Last reply
More about sli option nvidia possibly pci x16 issue
  1. Gigabyte has an odd way of advertising the sloot configurations. If I am reading newegg right while wrestling with their format, you have the 2nd one in the wrong slot.


    It says here that they are two x16 slots. Read the 2nd and 3rd paragraph there to see how the slots are configured.

    You should be using.....

    One GFX card - the one labeled PCIEX16 .... operates at x16
    Two GFX cards - above stays, new one uses the one labeled PCIEX8 * ..... both operate at x8

    It would appear from what GPU-z is identifying that you have it in the PCIEX4 slot

    If you put anything in the 3rd slot (your sound card), you wind up with x8, x4, x4 which would be a bad thing. X4 does not have the bandwidth for GFX

    Take the sound card out, make sure the two cards are in PCIE16 and PCIE8
  2. Thank you for your quick response Jack.

    I decided to go with my gut instinct and leave both graphics cards exactly where they are. However, I did remove the sound card and.... low and behold, Sli is live and kicking.

    Seems like the sound card was dragging the second card into an x4 state. Bizarre.

    I couldn't find a suitable answer in all my searching on the internet regarding this problem. I hope that others find their answer as straight forward as this solution was. I use a head set and mic anyways at all times so I won't really miss the sound card.

    Thanks again for your help Jack and to all of the Tomshardware community.
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