Don't Use a Vacuum to Clean Computer Fans while they're On
I was wrong, I broke 4 fan blades off, 2 on 2 fans. I'm assuming it was from the rapid change in velocity caused by the negative air mass across the fans.
I've never seen anything like that. Got three new fans coming in from newegg, I figured if I'm replacing two broken fans I might as well replace them all.
This is a full tower server case with fans across the front, to be clear.
Feel The Power Of The Mark Side