Question Unable to detect all the graphics cards connected to motherboard ?

Mar 26, 2021
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I have an MSI H270 M3 Gaming motherboard with a celeron g3930 CPU. I have attached, 4 3070's to the motherboard and a PCIE wifi card. When I install 3 x GPUs (1 in the pcie 16, 2 in the PCIE 1 and the wifi card in the 2nd PCIE16 slot) everything runs fine. When I try to connect the 4th 3070, my system will not detect it. I have tried several configurations of my cards into the motherboard but I just can't get it to show 4th gpu in the device manager.

I was able to get it to show up once by placing the 4th card in the 2nd PCIE 16 slot but I kept getting an exclamation mark on one of the GPU in the device manager and it wasnt properly showing up. Then the PCIE wifi card would not work in the other PCIE slot. I can swap the PCIE wifi card to a USB but that still doesnt resolve my 4 GPU situation. I have 3 x GPU and my mobo, CPU, ram connected to a 1000 W PSU and the 4th GPU connected to.a 750W PSU. Trying the cards individually shows that they work so they are not bad cards. Any suggestions? Thanks
 

jasonf2

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Oct 11, 2015
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Looking at the spec on the Celeron you only have 16 pci lanes regardless of slots on your motherboard. I am pretty amazed that you are able to get more than two cards fully operational on that system even if you shut off everything else that uses pci . This is why people spend bank for HEDT chipsets that support 40+ lanes of PCI.
 

jasonf2

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After thinking about this for a little bit I am actually amazed that you can get more than one to work. My guess is you are getting them to detect, but only due to the fact that the motherboard is physically cutting the lanes to the cards which would want 8x each for operation. Considering that 4x would be necessary for a nvme drive or at least 4 for sata/usb there is no physical way to boot even running two cards at full channel capacity. Again you may be getting the os to detect the cards but they are probably not running at full tilt. With the system configuration you are throwing I am assuming that you are mining, which is pretty intensive on cards so even if you are somehow magically getting something to pass to the three my guess is that your hashrate is greatly reduced due to pci bandwidth being reduced to a crawl.
 

Zerk2012

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I have an MSI H270 M3 Gaming motherboard with a celeron g3930 CPU. I have attached, 4 3070's to the motherboard and a PCIE wifi card. When I install 3 x GPUs (1 in the pcie 16, 2 in the PCIE 1 and the wifi card in the 2nd PCIE16 slot) everything runs fine. When I try to connect the 4th 3070, my system will not detect it. I have tried several configurations of my cards into the motherboard but I just can't get it to show 4th gpu in the device manager.

I was able to get it to show up once by placing the 4th card in the 2nd PCIE 16 slot but I kept getting an exclamation mark on one of the GPU in the device manager and it wasnt properly showing up. Then the PCIE wifi card would not work in the other PCIE slot. I can swap the PCIE wifi card to a USB but that still doesnt resolve my 4 GPU situation. I have 3 x GPU and my mobo, CPU, ram connected to a 1000 W PSU and the 4th GPU connected to.a 750W PSU. Trying the cards individually shows that they work so they are not bad cards. Any suggestions? Thanks
Are you using risers for the cards?
Same processor their using 8 cards.

View: https://www.youtube.com/watch?v=YJYJJHpGyXo
 
Mar 26, 2021
3
0
10
0
After thinking about this for a little bit I am actually amazed that you can get more than one to work. My guess is you are getting them to detect, but only due to the fact that the motherboard is physically cutting the lanes to the cards which would want 8x each for operation. Considering that 4x would be necessary for a nvme drive or at least 4 for sata/usb there is no physical way to boot even running two cards at full channel capacity. Again you may be getting the os to detect the cards but they are probably not running at full tilt. With the system configuration you are throwing I am assuming that you are mining, which is pretty intensive on cards so even if you are somehow magically getting something to pass to the three my guess is that your hashrate is greatly reduced due to pci bandwidth being reduced to a crawl.
No this is actually very common for the cards with risers. My hashrates for the 3 cards are actually above optimum at 61 mh/s. This is not the same as worrying about sli or crossfire.
 

Zerk2012

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Yes I am using risers and there are no issues with the individual card or riser as tested them individually and together
Have you tried it without the WIFI card.

From the board details


• 2 x PCIe 3.0 x16 slots (supports x16/x4 mode)*
• 4 x PCIe 3.0 x1 slots
* The PCI_E4 slot will be unavailable when an M.2 SSD module has been installed in the M.2_2 slot.
** The PCI_E2 slot will be unavailable when an expansion card has been installed in the PCI_E5 slot.
** The PCI_E3 slot will be unavailable when an expansion card has been installed in the PCI_E6 slot


EDIT from the way that reads you can just use 4 slots I would try the top 4 slots without using the WIFI card. Might need a USB WIFI.
 
Last edited:

jasonf2

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As I see it you still have too few lanes available for the slots you have. You can only use 2 of the x1 slots at a time plus both long slots assuming you aren't using M.2 (then only slot 1). The only way I have seen is to purchase a 1x to 4 splitter card from amazon and run it on one of the 1x slots. Then you should get all 4 on one 1x slot anyways. So as you sit without the splitter max will be 3 cards as it sits.
 

Zerk2012

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As I see it you still have too few lanes available for the slots you have. You can only use 2 of the x1 slots at a time plus both long slots assuming you aren't using M.2 (then only slot 1). The only way I have seen is to purchase a 1x to 4 splitter card from amazon and run it on one of the 1x slots. Then you should get all 4 on one 1x slot anyways. So as you sit without the splitter max will be 3 cards as it sits.
No 4 cards using the top 4 slots, if he needs the WIFI buy a USB WIFI.

You don't use 2 X M.2 drives on a mining rig probably is using none. The top M.2 slot has nothing to do with the PCI-E lanes.
 

jasonf2

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Oct 11, 2015
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You are right. I didn't see that the M.2 restriction for the x4 slot was only on the second m.2 slot. Should work if no additional PCI are attached except the video cards and slotted correctly in E1, E2, E3 and E4 and M.2 is in slot one.
 

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