Hi everyone!
So, 40 days have passed since i got my HMD (replaced motherboard of HMD) from service centre in Moscow.
I playing everyday for 2-3 hours, and i don't get grey screen.
When i just plug hmd to AC when it cold, i dont get grey screen anywhere. Then, if i have playing for ~1 hour, and HMD get hot, i get grey screen when position of my HMD over PC table and very close to it. Perhaps, reflections of objects on the table, interrupt beam trajectory, and i think it's normal reason and not is not attribute of malfunctions. I expect any heated HMD be losing tracking in similar cases.
Now, I am satisfied with the result. But i spand a lot of time and power for find decided. I should was ask for help to service centre, not community.
Thanks for everyone, who tested and shared own results and search this problem.
, did you to HTC service center?