2nd graphics card not detected

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Setting Sun

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Aug 14, 2013
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I'm trying to get my dual GTX 780's running in SLI, but my second card isn't being detected. The fans are running so I know it has power, but the LED lights near the power connectors aren't on and nvidia control panel isn't giving me an option to enable SLI.

I'm using the Asus Maximus VI Hero Motherboard, and running Windows 7 home premium OS.
the 780's are the Asus DC2OC models.

Power supply is Corsair AX860 platinum certified
 
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MarkW

MarkW

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Dec 7, 2009
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Are you putting the video cards in the 2 red slots closest to the CPU?

In the image below, I put a big blue arrow where the main video card should be. The second video card should be in the next red slot over.

126bgwk.jpg
 
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S

Setting Sun

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Aug 14, 2013
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Yes, both of the cards are seated in the Red PCI-E slots
 
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MarkW

MarkW

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Dec 7, 2009
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I am reading the gobbly goop that asus puts as footnotes on that motherboard, and I cannot tell you with any certainty that the second red slot is actually functioning at 8x. Is there any other card inserted into a PCIe slot at all?

Nvidia requires 8x PCIe lanes per slot to do SLI. I suspect that for some reason, something is using a lane, and that means that the Nvidia drivers are seeing that the second slot has less than 8x PCIe lanes, and when that is the case, the second card is put into sleep mode, and SLI is disabled.
 
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Setting Sun

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Aug 14, 2013
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I only have the 2 cards. In each of the red slots. Perhaps I need to change my PCI settings in Bios? How do I get it to read the second slot as 8x?
 
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MarkW

MarkW

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Dec 7, 2009
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It should happen automatically.

When a single video card is in the red slot closest to the CPU, it gets all 16x PCIe lanes.
When a card is in the first two red slots, the lanes become 8x/8x. That is all that Nvidia requires for SLI.

You should not need to change anything in the BIOS.

Download DDU and run it. It will ask to go into Safe Mode to do its thing. Select Yes when it asks.
In Safe Mode, it will offer you 3 choices. Select the top one (recommended), and let it do its thing.
Once it is done, restart your system, and let it boot to the desktop.
Download the latest Nvidia drivers, and install them.

See if that fixes things.

The two logo's below are links to their download pages.


 
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S

Setting Sun

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Aug 14, 2013
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Do I keep the SLI bridge connected and both GPU's installed while doing this?
 
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Setting Sun

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Aug 14, 2013
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Ok I ran DDU in safe mode, and re-installed the drivers. No change.
 
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Setting Sun

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I found the solution. the 2nd GPU wasn't fully slotted in the pci slot, because I installed the 1st GPU, then tried installing the 2nd one under it where I couldn't see the slot very well. I pushed it snugly in and everything is working now. lol.
 
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rolli59

rolli59

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Oct 27, 2007
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Really first thing to check but enjoy!
 
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