# Can’t get 4 GPUs to work (1 is connected via M.2 to PCIe)



## Crypto_Miner (Sep 13, 2021)

Hi,
I have an ASUS TUF GAMING B450M-PRO S Micro ATX that I can’t get 4 GPUs to work on. I wouldn’t have chosen this mobo for mining but was part of a Newegg shuffle win. 3 GPUs work perfectly but I was hoping to leverage the two M.2 slots to add 2 more GPUs (rig has a 1300W PSU). I am using a M.2 to PCIE 1x adapter. When I connect 4th GPU to M.2 slot closest to CPU, it doesn’t show up and BIOS says no NVME device detected. I moved the adapter to M.2 slot in between PCIE 16x slots and the new card showed up but it replaced the card in the second PCIE 16x slot. BIOS allows me to choose M.2 or PCIE (Auto mode defaults to M.2 device if detected), so I changed it to PCIE, and I can see the 3 original cards but not the new card connected via M.2 adapter. Is there a way to make this work?

Thanks in advance!

Mobo expansions slots specs:


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## plastiscɧ (Sep 13, 2021)

*U activated all the right settings?*


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## Crypto_Miner (Sep 13, 2021)

I don't see these options in my BIOS. Here's what I have for onboard devices:




For PCI Subsystem:


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## Toothless (Sep 13, 2021)

plastiscɧ said:


> *U activated all the right settings?*
> 
> View attachment 216696
> View attachment 216697


Why are your pictures distorted? Looks like a really bad printer accident.


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## plastiscɧ (Sep 13, 2021)

Crypto_Miner said:


> I don't see these options in my BIOS. Here's what I have for onboard devices:
> View attachment 216706
> 
> For PCI Subsystem:
> ...


then i fear, if u had read my bios options, i cant help u OR u cannot put that 4th card in and activate it. one out of two. but i will be honest; i am out here. not to say false things



Toothless said:


> Why are your pictures distorted? Looks like a really bad printer accident.


its a panorama handy pic very near shot on a curved widescreen monitor. its the bios screen. so no screenshot possible


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## Crypto_Miner (Sep 13, 2021)

I think you're right, I will not be able to add a 4th GPU via M.2 to PCIe with my current cpu/mobo. I read the mobo specs carefully and it says that M.2_2 shares bandwidth with PCIEX16_2, so whichever one is enabled, the other gets disabled. Also, mobo specs list M.2_1 supporting PCIe mode with Ryzen Gen1/2/3 but I have an Athlon 3000G not a Ryzen, so M.2_1 can only be used for storage. I am probably better off ditching the M.2 to PCIe adapter and going with a 1x2 or 1x4 PCIe splitter, although I am not a fan of those splitters for long-term use.


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## sound_source (Dec 10, 2021)

Crypto_Miner said:


> I think you're right, I will not be able to add a 4th GPU via M.2 to PCIe with my current cpu/mobo. I read the mobo specs carefully and it says that M.2_2 shares bandwidth with PCIEX16_2, so whichever one is enabled, the other gets disabled. Also, mobo specs list M.2_1 supporting PCIe mode with Ryzen Gen1/2/3 but I have an Athlon 3000G not a Ryzen, so M.2_1 can only be used for storage. I am probably better off ditching the M.2 to PCIe adapter and going with a 1x2 or 1x4 PCIe splitter, although I am not a fan of those splitters for long-term use.


Hi, have you already tried out the 1x2 PCIe splitter? does it work that way? i´m have the same issue, using the M slot disables my 16x slot. And OS does not detect the 4th gpu


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## mstenholm (Dec 10, 2021)

plastiscɧ said:


> then i fear, if u had read my bios options, i cant help u OR u cannot put that 4th card in and activate it. one out of two. but i will be honest; i am out here. not to say false things
> 
> 
> its a panorama handy pic very near shot on a curved widescreen monitor. its the bios screen*. so no screenshot possible*


How to make screen shots of BIOS @plastiscɧ It's possible but it involves a USB stick and a little bit of work


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## Crypto_Miner (Dec 10, 2021)

sound_source said:


> Hi, have you already tried out the 1x2 PCIe splitter? does it work that way? i´m have the same issue, using the M slot disables my 16x slot. And OS does not detect the 4th gpu


Hi, yes I've been using 1x4 PCIe splitter but I only have two cards plugged into it for almost 3 months now and no issues.


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## Mussels (Dec 14, 2021)

Crypto_Miner said:


> Hi,
> I have an ASUS TUF GAMING B450M-PRO S Micro ATX that I can’t get 4 GPUs to work on. I wouldn’t have chosen this mobo for mining but was part of a Newegg shuffle win. 3 GPUs work perfectly but I was hoping to leverage the two M.2 slots to add 2 more GPUs (rig has a 1300W PSU). I am using a M.2 to PCIE 1x adapter. When I connect 4th GPU to M.2 slot closest to CPU, it doesn’t show up and BIOS says no NVME device detected. I moved the adapter to M.2 slot in between PCIE 16x slots and the new card showed up but it replaced the card in the second PCIE 16x slot. BIOS allows me to choose M.2 or PCIE (Auto mode defaults to M.2 device if detected), so I changed it to PCIE, and I can see the 3 original cards but not the new card connected via M.2 adapter. Is there a way to make this work?
> 
> Thanks in advance!
> ...


It literally says "actual support may vary by CPU"

So... what CPU is in there?


If its the Athlon you mention a few posts later, that's going to be the issue - the text you posted says that CPU's with onboard vega graphics only work with SATA devices in the M.2 slots, because the chips with onboard graphics dont have enough PCI-E lanes to run everything at once


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## newtekie1 (Dec 14, 2021)

Mussels said:


> If its the Athlon you mention a few posts later, that's going to be the issue - the text you posted says that CPU's with onboard vega graphics only work with SATA devices in the M.2 slots, because the chips with onboard graphics dont have enough PCI-E lanes to run everything at once


That's the issue with the top M.2 slot. The bottom one is run off the chipset, but the chipset doesn't have enough lanes so the bottom M.2 slot shares lanes with the bottom PCI-E x16(x4) slot. So only one can be used at a time.


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## Deleted member 24505 (Dec 14, 2021)

plastiscɧ said:


> *U activated all the right settings?*
> 
> View attachment 216696
> View attachment 216697



Your pics are NOT for a Tuf Gaming B450m-Pro s motherboard



Crypto_Miner said:


> Hi, yes I've been using 1x4 PCIe splitter but I only have two cards plugged into it for almost 3 months now and no issues.



His pics are not for your board as it does not have a Q-code led. I don't what board the pics are from he has posted.


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## Mussels (Dec 15, 2021)

Looks like the athlon CPU's cut off a ton of PCI-E lanes from everywhere
Google-fu says 4x lanes for GPU and 2x for chipset, which then comes down to where the board places the remaining lanes (NVME, 1x slots, etc)


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## lexluthermiester (Dec 15, 2021)

Mussels said:


> If its the Athlon you mention a few posts later, that's going to be the issue - the text you posted says that CPU's with onboard vega graphics only work with SATA devices in the M.2 slots, because the chips with onboard graphics dont have enough PCI-E lanes to run everything at once





Mussels said:


> Looks like the athlon CPU's cut off a ton of PCI-E lanes from everywhere
> Google-fu says 4x lanes for GPU and 2x for chipset, which then comes down to where the board places the remaining lanes (NVME, 1x slots, etc)


This.

@Crypto_Miner 
You need to install a Ryzen 5 model CPU to make 4 GPUs work on that board. An Athlon or Ryzen 3 will not meet the required number of PCIe lanes.


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## Mussels (Dec 15, 2021)

lexluthermiester said:


> This.
> 
> @Crypto_Miner
> You need to install a Ryzen 5 model CPU to make 4 GPUs work on that board. An Athlon or Ryzen 3 will not meet the required number of PCIe lanes.


All the desktop models without IGP get 24 lanes
Ryzen 5000g series chips get 24 lanes

The ryzen 2000/3000/4000 series with IGP get 20 lanes


Athlon 3000G has even less at 12 lanes


Anything Athlon, is gimped. hard.


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## lexluthermiester (Dec 15, 2021)

Mussels said:


> All the desktop models without IGP get 24 lanes


I thought the Ryzen 3 model got less. Had to look it up. Seems I was thinking of the mobile Ryzen models...

Even a GPU mining rig requires a reasonable CPU to keep it all running.


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## plastiscɧ (Dec 16, 2021)

Mussels said:


> All the desktop models without IGP get 24 lanes
> Ryzen 5000g series chips get 24 lanes
> 
> The ryzen 2000/3000/4000 series with IGP get 20 lanes
> ...


very well broken down and explained. i am not as at home with AMD as i am with intel. so you definitely have a good transition to the other system.


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## newtekie1 (Dec 16, 2021)

Mussels said:


> Looks like the athlon CPU's cut off a ton of PCI-E lanes from everywhere
> Google-fu says 4x lanes for GPU and 2x for chipset, which then comes down to where the board places the remaining lanes (NVME, 1x slots, etc)


Yeah, the link from the CPU to the chipset is gimped, but that isn't what is causing the bottom PCI-E x16 and M.2 to share lanes. That's just a limitation of the B450 chipset no matter what CPU is used.


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