Very close to completely silent, eco mode PSU with fan not running almost all the time. GPU fanless mode till 59c.
ML120s and 140s, so no bearing noise from fans at all, at full blast 2000 rpm they're extremely loud, but at 500 or so rpm are as quiet as be quiet silent wings at same rpm that I use on my cpu cooler.
Had to stop using HDDs even for storage as they were by far noisiest part of my system, been using SSDs only for 5 years.
Some fan wont let you tune them to silence in bios due to having a minimum operational rpm, but you can use software like Argus system monitor to override that in software. I kept a Corsair AF 140 for that reason that normally has 700 rpm minimum and is loud, on startup Argus is set to switch it to 500rpm at which point you can barely hear anything.
Most all fans set at 500rpm or lower at idle will make for a very quiet to silent PC. I actually highly rate MLs for that purpose as there will never be any bearing noise from them at all and they're just as quiet as quiet designed fans at low rpms.