Hello mikeywith.
I have to say, you were right. 

I've already solved this problem.

The problem was at PSU, It was so dirty in the air intake where the fans are, that it couldn't get any fresh air in, It was completely covered with dirt. I guess the PSU components overheated and sent the wrong voltage to the hashboards

After cleaning the PSU my T17 works correctly again. 

Thanks!!!