A:Answer The stock case fans were fine at idle, but under load I found them quite loud. You can play with the temp/speed curves, but bottom line was if the fans were spinning at %100, then I found them intrusive...
I replaced them with few ASUS ROG Strix fans (overkill but were on a deal), and the system is significantly quieter with them, even at %100 fan speed.
That was literally my only nitpick with this system, and it was definitely not a deal breaker for me, just a personal decision to replace the fans.