double GPU's with no SLI or such can't see secondary GPU

mikkelpriisholm

Commendable
May 24, 2018
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1,510
I got two GPU that i want to use in my pc. My main GPU is a "ASUS Strix GeForce GTX 960" and the GPU is a "Quadro FX 580" and i know it isn't the best. I want to use my main GPU for my main monitor as gaming and such. And the other GPU is just for my other monitor for Spotify or other. BUT my BIOS says that my secondary GPU is connected but it can't see it and i can't control it. There is not used any SLI or such as i just want to use them separate.
 
Solution


The PCIe 3.0 x16_2 slot on the ASUS Z170-P D3 motherboard only has four PCI Express lanes wired to it. NVIDIA graphics cards usually require at least eight PCI Express lanes to function. AMD graphics cards will function with a minimum of four PCI Express lanes.


If you want to use them separate I would recommend getting another PC or using a VM with the Quadro passed through to the VM.
 

ASUS Z170-P D3 and the main GPU is installed in PCIEX16_1 and the other is in PCIEX16_2, if that's what you mean.

 

I read that i could use two GPU's in the same pc without them being connected like through SLI. So that they did each their own job.
 


The PCIe 3.0 x16_2 slot on the ASUS Z170-P D3 motherboard only has four PCI Express lanes wired to it. NVIDIA graphics cards usually require at least eight PCI Express lanes to function. AMD graphics cards will function with a minimum of four PCI Express lanes.
 
Solution

Okay i think i understand it. Thanks!

 
 
 


You will need a motherboard that is SLI capable. Your ASUS Z170-P D3 is only AMD CrossFire capable and is currently why your second NVIDIA card isn't being recognized.
 


Actually, that's not why, but your close. The board isn't SLI certified, so you can't run GPU's in SLI. However, you still can run 2 cards on a non SLI board, just not in SLI. The reason is the second "16x" slot is only wired to run at 4x, and Nvidia cards need at least an 8x connection to work and be recognized. Also, you said your using the second GPU for Spotify and stuff? That will barely use 1-2% of your GPU and you'll see pretty much no loss in FPS with just the GTX 960, I see no point to having the Quadro installed unless your doing GPU intensive tasks like video editing on your second monitor while gaming.
 


The 4 lanes in the PCIe 3.0 x16_2 slot on the ASUS Z170-P D3 motherboard are only wired to the Z170 chipset and not directly to the CPU socket.

The PCIe 3.0 x16_1 slot on the ASUS Z170-P D3 motherboard has all 16 lanes of its PCIe slot wired to the CPU socket with no lane splitting capability.

An SLI capable motherboard will take the 16 lanes wired to the CPU and split them into 8 lanes to each graphics card when the second graphics card is installed.
 


This isn't an SLI capable board, which means the 4 lanes to the second physical 16x slot won't allow the second Nvidia GPU to work since Nvidia cards require at least 8 lanes. You could get an AMD card for cheap if it is really necessary to have a separate card for a second monitor since AMD cards run at 4x
 

This is wrong, you're thinking of SLI/Crossfire requirements. You can use either an Nvidia or AMD card with 4 lanes. Or even less, I've got a display from an AMD card with a x1 connection.

@mikkelpriisholm your CPU almost certainly has integrated graphics, which would be fine for running a second monitor for basic desktop stuff like spotify. You could just enable the iGPU in the BIOS and plug the 2nd monitor into the mobo display outputs. To be honest, even just running the 2nd monitor off the 960 would have negligible effect on gaming performance.
 
Yes, as far as I can tell the Quadro should be working, I'm not sure why it isn't. Have you tried plugging in just the Quadro in the 1st PCIe slot to see if it even works on its own?

But as I said, I don't see the point of using a second card in the first place...
 


The slot is physically a 16x slot, but it's missing pins in it which only lets it run at 4x, Nvidia cards require 8 which is why it won't work.
 


Yes, they don't need 8x for non SLI, but currently that board doesn't know that there isn't SLI. Also, what CPU is the OP using and is the OP using NVME storage or other PCI-E devices? There may not even be any open CPU lanes for the second card.
 
The system shouldn't default to trying to run the cards in SLI, especially given that you couldn't SLI those cards even there were sufficient PCIe lanes. I'll admit I've never run multiple Nvidia cards myself, but I've had multiple , different AMD cards in my rig and they didn't automatically try (and fail) to crossfire.

Also, the 2nd physical PCIe x16 slot (the one the OP has plugged the Quadro into) doesn't share PCIe lanes with any other slots. So it doesn't matter what other peripherals are connected.
 


Yes, but if the CPU's lanes are being used by other devices that use lanes the card wont have any to use. Like, a CPU with 32 lanes can't run 4 GPU's and NVME M.2 Raid even if the CPU has enough cores and is fast enough not to bottleneck.