RTX 4000 Mosaic SLI performance and rendering issues

Performance is not good, vkcube content dissapears when moving across GPU cards in 2x3 configuration. Please advise

Nvidia driver 535.161.07
Xubuntu 22.04 kernel 6.5.0-26-generic #26~22.04.1-Ubuntu

GRUB_CMDLINE_LINUX_DEFAULT=“nomodeset drm=0 iommu=off”


I had to put my configured xorg.conf contents into:
or SLI mosaic would fail

options nvidia-drm modeset=0

blacklist nouveau
blacklist lbm-nouveau
alias nouveau off
alias lbm-nouveau off

sudo cat /sys/module/nvidia_drm/parameters/modeset

uploading nvidia-bug-report.log.gz gets stuck
“Processing” on this forum

Please try to unzip and upload the log.

Please see attached.
nvidia-bug-report.log.gz (2.5 MB)
thank you

Setup looks fine but there are a lot of errors (memory unmap errors, Xid 32, 56, segfault of nvidia-settings, vulkaninfo) that would rather point to a hw issue, either pcie slot or system memory. Tried reseating/changing slots? Memory set to stock clocks or overclocked/xmp active?

Thank you for the suggestion. Stock clocks and I will try re-seating components or plugging them in one by one. Once the machine is available to me again. Please leave this open until I can report back next week.

Just to update in my first report I showed iommu=off in my grub config, but I actually used amd_iommu=off (as the motherboard is AMD based) to get to the state I was in during my report. Since then I’ve not had much time to disassemble the PC but I did update the bios and try some other linux distros (manjaro, debian) with similar if not worse results. I also updated the bios as I had to reflash. Here is an updated bug report and I’m no longer getting the Xid errors but getting segfaults from vulkaninfo and libnvidia-glcore.so.535.171.04
nvidia-bug-report.log.gz (2.2 MB) Performance is still bad with tearing as well and vkcube content is cut-off between GPUs.