@Swedishkiller12 Undervolting a 12V fan on the Pis 5V or even 3.3V pin is not going to give you any benefit. In fact it most likely is going to move a lower volume of air then your 5V fan on the 3.3V rail.
Fan noise really comes down to two things. Air turbulence (fan speed/fin design) and ball bearing quality/noise.
Spinning your fan slower and having an adequate passive cooler on the SOC is likely your best bet.
Have you measured/logged temperatures while under load? If you can do this while running on the 3.3V pin and are staying below the ideal max of 70C (this is not the absolute max, but rather the safe longterm max for most models) then you should be fine.
My first impression about the new case (BIQU Aluminium case) is fantastic. It dropped at least 20° Celsius while idling or watching preview videos at around 52° even with moderate overclocking (arm_freq=1300 core_freq=500 sdram_freq=500 over_voltage=2). Before this case, it was sitting around 70° without any overclocking. Now, I don't know how to test properly, but I am happy if it stays stable and cool and if I don't get any over heating warning symbol while playing 8- and 16-bit console games with shaders.
In my arcade build i found the fan that came with the flat pack kit was really loud when run from full power. It was a 12v fan. So i just found a left over 5v power brick and connected that to the fan and it runs about half speed, just the perfect amount of air flow without the noise.
@ethanmlego there is a very technical equation to determine the closeness of the fan, size and rating of cpu, and the size of the fan.
But I will simplify it as distance should be directly proportional to the size of the fan. Judging by the distance away I'd recommend the following fan:
Primary concern would be to have proper ventilation to pull out the hot air being dissipated by the heat sink. I would recommend trying a few different placements while checking the temp from the terminal to see what works best.
@ecks What other devices and controllers do you use the USB? What is power rating on the fan that you will be using? Does it have any labels on it?
There is no label saying anything about the power rating on it which you can see in the images and like i said USB wise for cords i use it for my game controller and phone to recharge the only thing i have left if an old micro usb charger but it is not even 5 volts it is more like 2 or 3 volts instead (was made for a super old flip phone)
You need to reverse that. Most fans are going to need 5v to run. You can also use the 3.3v pin (pin escapes me right now), to run fans quieter, but those are the pins to run fans on for the pi. Also recommended are heatsinks for all of the sensitive chips (including the one on the bottom of the board). Use pins 2 and 9 for the power switch but not recommended for corrupting the sd card. I got one of the push button switches that connect to the micro usb port in between the pi and the power supply. It will also clean up your power feed.