I'm tired.. Why is my DELL G3 3579 fan making lots of noise?

If you have not replaced the heatsink pads, that should be done.  If the noise continues, replace the fans.

It's not about the fan speed, it's about the noise. It's not the sound of a fast fan, it's the sound of a motor/helicopter/grinding/motorcycle, etc. 

Do you understand what I mean? 

Additionally, these fans here in my country cost 1600 Egyptian pounds; that's a fortune.

The only thing in that system capable of making that much noise is a fan or a hard drive motor.  Even coil whine, while annoying is not that loud  -- and it's far higher in pitch.

If the system has a hard drive, remove it and see if the noise disappears.  If it does, replace it with a solid state drive.

Otherwise, replace the fans -- since the price you quote translates to just over $30 US, they're actually less expensive there than the US.

https://www.parts-people.com/index.php?action=search&search=G3+3579+fan

I don't have an extra hard drive; I only have the main one.

And these fans are so expensive here. Do you want me to buy them from the US? I'll end up paying a fortune in customs fees.

Your quoted 1600 pounds is $31.68 so it'll be cheaper to buy locally.

Unfortunately, you can't solve the problem by waving a magic wand -- either the fans or the hard drive needs to be replaced.

@MarinaHousley​ Going by your description, the fan's bearings are likely bad. The fan will need to be replaced.

You can try disassembling the fan and apply a drop of oil onto the bearings, but if that fixes the anything, it will be only be short term.

Yes, it seems that replacing the fans is the best option to alleviate my headache. However, I can't help but wonder: Why do so many people online have fan problems with this particular model [DELL G3 3579]?

Thank you all very much. You are all very kind, and your manner of speaking and conversing is quite refined.

Did you try updating the bios and changing the theminal paste on the processor ? You should try those out... it should solve the issue