I have asked hardware team, they have tested, and can be sure there are no
power supply problem.

The system is arm64 with 64 cores. and there are three amdgpu card in the
board.

there are rarely gfx timeout, sdma timeout, and vce timeout. When the ring
timeout occur, we can use amd supplied tools umr to read chip registers. can we
know the real cause from the register value?

with the coherency problem you said, I think if that was true. the problem
should occur more frequently. I'm not sure.