Dell G3 15 (3579) fan makes strange noise

Every time the Gpu fan on my Dell G3 3579 starts up at low revs, it makes strange sounds — a creak or a roar. They are not constant - they appear, then disappear, but it is heard only at low speeds. It's not a hdd or ssd Im' sure - they have another sound. The fan on the processor does not make such sounds. I did a BIOS test - no errors. I asked to a service center in my city - they did the cleaning, but the problem did not go away. Since the laptop warranty service center filed an application to Dell Ukraine to replace the fan and had to talk with technical support from Dell. The guy from phone support offered an incredible diagnostic - bring the phone to the fan during the conversation and then he said - I can't hear anything, you have no noise (but they are), I will not approve your request for a replacement. It made me very angry. Who in 2019 diagnoses by the sound of a telephone conversation. What do I need to do in this situation? Can I replace the fan for my money - it is very annoying with its creak?