Just dust the case and/or adjust the fan curves. They're loud cause it's dirty.
I second cleaning the PC. Dusted out my case a week or so ago and noticed that some tasks that previously made the fans ramp up audibly it now doesn't at all or way later.
If you have some sort of compressor for air blowing you don't need to disassemble much, just take the sides and all dust guards off. If you want to be cautious make sure the fans don't rotate as it produces current and cheap fans save money by leaving out protection measures.
Some people also do it with canned air although I don't know for how many appliances one can lasts.
Just make sure to do it outside.
Last I think it's fair to mention that, at least with a compressor, you'll most likely get condensed water into your PC. I've cleaned my machine several times that way and didn't have issues. Always made sure to spray a good bit on the side panels after I was done with the machine so I could make sure the water was evaporated before I plug the PC back in.
It's apparently indeed none conductive, as they teach in school, but it still feels sketchy.