If you see something like this in the dmesg:
NVRM: Xid (PCI:0000:01:00): 79, pid=17169, GPU has fallen off the bus.
NVRM: GPU 0000:01:00.0: GPU has fallen off the bus.
NVRM: A GPU crash dump has been created.
means its GPU on bus id 01. How to find the GPUs Bus ID
- while the error GPU has fallen of the bus.
tells us this GPU has problem with riser, power to riser or power to the GPU.
Example of damage after receiving the "GPU has fallen off the bus" message: