.

[AnotherTechGuy]

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[MegaDave91]

Have you enabled SLI in the Nvidia CP?

[AnotherTechGuy]

Have you enabled SLI in the Nvidia CP?

The option isn't available, will post  screenshot in 2 mins

[AnotherTechGuy]

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[Caimath]

I have never used SLI, ever, but can you SLI 2 cards if they have different PCBs? I know some manufacturers make small changes / reworks parts of the PCB. (I also don't know if either of those have a non-reference PCB)

 

Edit: Also, why would you buy a different manufacturer card for your secondary card?! Ruins the symmetry!

 

Edit 2: A short google search confirmed that it is in fact possible to SLI cards with different PCBs, so feel free to ignore my question.

[MegaDave91]

http://gyazo.com/8a1c04c9a4a115c3464bfebd80351abb

 

Have you checked the bios for pcie3 lane options? 

[AnotherTechGuy]

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[jmaster299]

This won't fix your current issue, but always set Physx to auto, never to CPU. Physx games have not supported CPU Physx for a couple of years now.

 

[jinroh10]

Do you have the SLI cable installed? And in the Nvidia control panel you have to enable sli.

[AnotherTechGuy]

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[jinroh10]

What version of the Nvidia control panel do you have? Is your drivers for your primary gpu up to date. Try theses option and let me know.

[AnotherTechGuy]

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[jinroh10]

Try flipping the sli bridge around, do you have all cables needed to power the gpu installed?

[jinroh10]

Also try and making the primary card the second and make the new card the primary just to make sure the card is functional and or the pci express slot is not having issues.

[Mick Naughty]

So it doesnt even show up in your device manager? 

What os are you on?

[MegaDave91]

Also try and making the primary card the second and make the new card the primary just to make sure the card is functional and or the pci express slot is not having issues.

This is probably your last option. If the newer card is not detected in the slot your first 780 is in then the other 780 is faulty.

[AnotherTechGuy]

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[MegaDave91]

Switched GPU PCI slots, SLI enabled

Could have been that the second card was not seated properly.

[Caimath]

Try getting a reference 780 in Australia.... they're more expensive than aftermaket.

That part was mostly a joke, I figured it would be something like that.

[jinroh10]

Switched GPU PCI slots, SLI enabled

See....I knew that would work, im glad that was able to resolve the issue because I had the same similar situation.