You can run GPU-Z and compare its specs with Gigabyte's GPU specs or click on GPU-Z upper right icon under "LOOKUP" and see if they are the same.
Sounds like your PSU fan is going bad and your PSU is overheating. Which probably mean that it is a good chance it isn't outputting proper voltages to your Motherboard and hardware when it is overheating. This improper voltage could damage your PC hardware.
Make sure that the PSU is where you are hearing the noises and that the PSU is very hot to the touch before replacing it.
My wife's PSU fan stopped (OEM PSU from Ibuypower PC) working and the PSU burnt up. Replaced it with a Corsair 850 Watt PSU and now everything is working great again for my wife's PC.