Score:0

Ubuntu won't start when I connect 8 AMD GPU

ke flag

I have a computer with:

  • Intel Celeron dual core 1.60GHz
  • 8GB RAM
  • x8 - Rx6700XT 12GB
  • HDD: 500GB

I installed Ubuntu 20.04 and when I start the machine after loading with the Ubuntu screen, it always comes out black screen with sometimes some of these errors. The strange thing is that if I connect only 6 GPUs the machine starts easily. As soon as I connect the 7/8 graphics card everything does not start. I don't have any problems with starting Windows on this computer.

Sometimes this error appears.

sometimes this error appears.

Other times it stays like this for hours.

other times it stays for hours like this

Pilot6 avatar
cn flag
It is not "Ubuntu won't start" it is there is not enough power for all your GPUs.
Pierfrancesco cp avatar
ke flag
everything is installed in dual boot with windows. No problems starting with windows
ru flag
Have you considered temporarily switching out one of the first six for the 7th and 8th GPUs you're connecting in the off chance the issue is a dead card? Are you *sure* you have the proper power supply to provide power to 8 GPUs? If you haven't validated that, that's your next step, Windows might hide / ignore those errors and disable the device and show it's malfunctioning, but it does sound like you have a power problem.
Pierfrancesco cp avatar
ke flag
Yes, I'm quite sure of everything: At the power level there are no problems because it is a configuration that I created about a year ago for mining and everything has always worked for the best without nenahce of overheating of the power cables. Now I was doing some experiments to try to do some deep learning. However, after having dismissed it from mining, I made sure that the power supply was intact (we are talking about 2000w made especially for gpu mining).
Pierfrancesco cp avatar
ke flag
I also made sure through Windows that the 8 cards were all intact through the device management on windows. I also tried to interchange them with each other and I realized that it's not the cards themselves but the number of cards that I'm going to connect
pl flag
According to `CONFIG_VGA_ARB_MAX_GPUS` I believe the max number of GPUs supported by the Linux Kernel itself is 16. But there may well be some other limit, perhaps in the AMD GPU driver subsystem, which is limiting that number more.
Pierfrancesco cp avatar
ke flag
ok, so theoretically it's a driver problem?
Pierfrancesco cp avatar
ke flag
or could it be a Vram Limit problem? Because with 8 cards I get 96gb of ram
us flag
have you tried a later Ubuntu version than 20.04? worth trying the latest release to get the latest kernel etc.
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