the fan is working but when it's I find it after I lose 4 cards, it's not running. I.e. protection mode I think.
Yes, it's Over-voltage protection, under-voltage protection, short circuit protection, over power protection, and over temperature protection.
Maybe one of that protection has happened to your PSU.
so the splitter could be issue? I had saame setup on another rig without any issues. hmmm
Not sure, But it can be. I just inform you about the Y splitter power issue.