DELL Desktop Inspiron One 2330 AIO PSU FAN Error 2000-0511 93901

1xPSU FAN

PSU fan or CPU fan? When you replaced the fan, did you get a Dell OEM fan specific for this model or some other brand? Dell fans have a sensor that's read by BIOS. Otherwise you'll get fan failure errors.

Is the CPU fan cable properly and securely connected to the motherboard?

You can try clearing BIOS to see if that eliminated the error:

1. Reboot and press F2 to open BIOS setup
2. Copy down all current BIOS settings
3. Power off and unplug
4. Press/hold power button for ~15 sec
5. Open case and remove motherboard battery
6. Press/hold power button for ~30 sec
7. Reinstall the battery (right-side-up)
8. Close case and reboot
9. Assuming that clears the fan error, go into BIOS setup again and make sure all settings match what you copied or change to match what you  copied. Be sure to save the changes when exiting setup.

Did you apply fresh thermal paste between the heatsink and CPU when you replaced the motherboards?

If none of that helps, try reinstalling the video card driver.

EDITED

Yes, PSU Fan from Dell PN: 6X58Y

Is the CPU fan cable properly and securely connected to the motherboard?: YES

Clearing BIOS do not helped. 

Did you apply fresh thermal paste between the heatsink and CPU when you replaced the motherboards?: YES

If none of that helps, try reinstalling the video card driver: Restored system to the original factory settings(OS Recovery), installed drivers from support.dell.com.

https://www.dropbox.com/sc/25000i5xqi3unej/AABAx7e_A7Ar4WiLOoHetfD9a

https://www.dropbox.com/sc/yxrakr14uc2iukf/AADBSZcf_x8suvQhMM_nF18ta

Have you tried replacing the processor heat sink fan?