Nvidia-smi not recognizing a second GPU RTX A6000

Hello! I’m trying to install a second GPU on a Dell Precision 5820 Tower and I’m facing some issues.
I currently have a T400 that is being recognized when I check, but after I added the second one (an RTX A6000), the system doesn’t start , and I had to reboot in recovery mode as I got the following message of power fault.

[ 2.976303] pcieport 10000:00:02.0: pciehp: Slot(91): Power fault
[ 2.985171] pcieport 10000:00:03.0: pciehp: Slot(92): Power fault

Below is the information of the slots where power fault was indicated.

10000:00:02.0 PCI bridge: Intel Corporation Sky Lake-E PCI Express Root Port C (rev 07)
10000:00:03.0 PCI bridge: Intel Corporation Sky Lake-E PCI Express Root Port D (rev 07)

Using nvidia-smi only the T400 one is recognized

But apparently both are installed:

lspci | grep VGA
0000:17:00.0 VGA compatible controller: NVIDIA Corporation Device 2230 (rev a1)
0000:65:00.0 VGA compatible controller: NVIDIA Corporation Device 1ff2 (rev a1)

Below is the error information I could find about the second GPU.

sudo dmesg:

kernel information:
fire@cima-fire-server:~/Desktop$ uname -a
Linux cima-fire-server 5.15.0-105-generic #115~20.04.1-Ubuntu SMP Mon Apr 15 17:33:04 UTC 2024 x86_64 x86_64 x86_64 GNU/Linux

Any ideas on how to fix it?
Thank you so much!