Ubuntu 22.04 Imac a1419 how to disable faulty nvidia graphic card to use only intel

Question

I have in iMac a1419 with faulty NVIDIA GTX780 graphic card.

I have build a full Ubuntu system on Samsung 128 GB USB drive. I'm booting into the system by pressing on keyboard "alt" key and selecting the external USB based drive. Generally speaking all is working fine,but I need to boot via advance options to force the graphic save mode or I get glitches on the screen.

I wonder how can I set Ubuntu 22.04 to permanently switch off/ disable the NVIDIA graphic card, so I can boot system the normal way not via safe mode.

Thank you in advance for any help.

I have run the the below suggested command to purge NVIDIA driver and rebooted the system. Booting the system normal way was stopped halfway with the above information (please see the screenshot). Booting to graphic save mode allow me to load the system, but that means no change to the case. Thank you in advance for any suggestion.

Thank you in advance for any help.

Welcome to AskUbuntu! Have you seen this answer? It goes through the basics of how you’ll need to do this — matigo, Jan 14 '24 at 05:07
If you are certain the hardware is faulty then sudo apt-get purge nvidia* and reboot then let us know the result. — darth_epoxy, Jan 14 '24 at 05:08
I have run the above result and screenshot added above, please check & advise. Thank you in advance. — Gregory, Jan 15 '24 at 08:17

Rolf · Answer 1 · 2024-02-01T20:27:41.953

I have a 27" iMac 15,1 I think from mid 2015 or something with AMD Radeon R9 M290X GPU hooked to an external display through DisplayPort.

I have OpenCore Legacy Patcher installed (OCLP) for running OSX 12.

I opened the case by separating the display and disconnected both connectors that go to the built-in LCD. Warning: this is a delicate operation! In my case someone did it before and they managed to crack the LCD and halve the value of the computer in the process, so I do not have this concern.

On the following boot the display output is routed to the external screen early in the boot process, I can even see the apple with the loading bar. So the external display became the main display for the system. I have not found any other way to obtain this result.

However the computer runs excruciatingly slow and the fan ramps up to maximum speed. So I check "disable firmware throttling" in OCLP, apply and reboot.

Now my computer seems to be running normally. The GPU temperature is much cooler and power consumption seems to have decreased. When I run graphic benchmarks the results are 2-3 times lower than the initial setup.

It looks like the GPU is disabled now but it's hard to confirm.

Ubuntu 22.04 Imac a1419 how to disable faulty nvidia graphic card to use only intel

1 Answers1