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NVidia GTX980 SLI Question

elohim3
Level 7
Hi all,
I have recently added a second Nvidia GTX 980 to my rig to give SLI a go. I have noticed that the motherboard is not allowing it to use a x16/x16 setup, and says it is running in x16/x8. If I look in the GPU post section of the Tool menu, it shows the card in PCIE_X16_1 linked at x16 Native, and the card in PCIE_X16/X8_3 linked at x8 Native.

I am running an Intel 5930k so I know I have 40 lanes to work with (also updated to 1801 BIOS just to make sure it wasnt that). Is there something I'm missing here that is preventing the second card from seeing all 16 lanes? (and yes, I know at PCI3.0 x16/x16 vs x16/x8 is supposed to be the same performance wise, but still... 😉 )
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21 REPLIES 21

Nate152
Moderator
Hello elohim3

It's probably due to your sound card as to why the 2nd gpu is running at x8, you could remove it then check to see if they're both running at x16.

Qwinn
Level 11
Nate is likely correct. If your sound card is in PCIE_X8_2, it's probably robbing more lanes than it needs (that is the slot that would be populated and use 8 lanes by a 3rd video card). Unfortunately, you can't put it in x8_4 because that would disable your M.2 drive. I suspect the PCIe 2.0 X4_1 slot may be your only option for the sound card that'll work..

Qwinn wrote:
Nate is likely correct. If your sound card is in PCIE_X8_2, it's probably robbing more lanes than it needs (that is the slot that would be populated and use 8 lanes by a 3rd video card). Unfortunately, you can't put it in x8_4 because that would disable your M.2 drive. I suspect the PCIe 2.0 X4_1 slot may be your only option for the sound card that'll work..


The PCIE_X4_1 slot would be the BEST choice given that his sound card is a 1x device. The only reason I don't have my 1x TV card in that slot is because when Fast Boot is enabled in Windows I can't stop the PC from waking just a few seconds after shutdown. I wouldn't mind knowing if elohim gets the same grief. Maybe it's just my TV card.
"Before you criticize someone, you should walk a mile in their shoes. That way, when you criticize them, you're a mile away and you have their shoes." -- Unknown

Hawkstorm
Level 7
You should be able to run in 16 16 mode with a soundcard I do.

Make sure you use both the 16 bit slots and try the soundcard in the bottom one.

Qwinn
Level 11
"Make sure you use both the 16 bit slots and try the soundcard in the bottom one."

As I mentioned earlier, the bottom slot is shared by M.2, which the OP has. If he plugs it in there, his M.2 drive will stop working. The slot he needs to use would be the x4_1 which is between where his 2 GPU's would be.

Sorry for the slow reply, had to work doubles all week to cover someone at work.

Just to eliminate the sound card all together, I pulled it out and fired the system back up. Same results with the card completely out of the system (x16/x8). I also made sure to disable any extra hardware like the wifi, bluetooth, and the sata express controller to make sure it wasn't a conflict somewhere else. I only have the M.2 drive, the storage array on the raid controller (3x1TB Raid 5) a bd-rw, a 3Tb sata drive for music storage, and the sound card in the system.

I do have the sound card in the 8_4 slot. The manual says that if you set the option in the bios to M.2 in the devices screen, it limits the 8_4 slot to x4 only and makes sure to dedicate resources to the M.2 slot (I did set this option to M.2).

Qwinn, I do have a question though. If the sound card is an x1 device electrically, how would it rob more lanes if it is only wired as an x1 device?


I am going to pull both cards tomorrow and try running the newer card solo and make sure it comes up as x16. Thanks for the ideas so far and let me know if you come up with something else I can try!

Pleot
Level 8
Dont know if this will help im not much literate in GFX cards but I had a problem with a card, it would allways work pci-e 2.0, so I went to BIOS and forced the slot to pci-e 3.0 and after that it would change to 3,0 under load and back to 2.0 when idle. So check if there is some parameter that can be configured in the BIOS

Menthol
Level 14
elohim3,
You are correct about the bottom RED slot, as long as the card you place is a pcieX4 or less it will not interfere with the M.2 drive.

Which 2 slots are you using for your GPU's?

Pleot - it shouldn't be necessary but there is a setting to set the slots to 2.0 or 3.0

54679

54680

Pleot
Level 8
Yes I had to force from auto to 3.0 to get it,
Also tried a single card on the other 16x slot, the fourth, realized it produced more heat on my cpu though it worked 16x 3.0,,,