Only #fans - Smol HP PC in use at local trade association making aircraft noise, turns out there are *two* fans inside this one - both had to be replaced. Second fan under HDD supplied with wrong connector (in spite of checking part number), as the correct ones were unobtanium (and even then there is 50% chance wrong one arrives) I had to #solder cable from old #fan (not fun job, 0,25mm cable and working with fingers just 10mm from soldering iron tip with 355°C (at least I managed not to burn my fingers ))

Now the PC is quiet again...