CPU fan is usually bios controlled once CPU reports temp from its thermostat to the fan controller.

No CPU fan means either dead bios or dead CPU, or other component fault drawing down a power rail.

No post fail or error message at all suggests motherboard but that depends on the vendor.

First check with multimeter all of the PSU rails while running and connected.

If PSU voltages bad, remove all power connections to PC, jumper the PSU motherboard enable pin and check again. If voltages ok without load, remove all components from motherboard, connect PSU and repeat voltage test. If bad, then a bad motherboard. If good, insert components until voltage is bad.

If you have a high speed oscilloscope you can try to check the PCIe bus for activity on startup and noise on the PSU. I don't know what equipment you have or spares for testing. 

 @Tyler 

Ty.  No post at all

Both motherboards and CPus are brand new and the fan don't spin.

The Motherboard is getting power because the USb keyboard lights up and ram lights up

The odds that both boards and CPu being bad can't be lol


What does this mean? 
"If PSU voltages bad, remove all power connections to PC, jumper the PSU motherboard enable pin and check again. " 

 RAM lights and fans and USB are 12v and 5v but that doesn't mean your 3.3v or negative rails are working.

https://www.lifewire.com/atx-24-pin-12v-power-supply-pinout-2624578

You want to simulate the motherboard by jumping the green wire to a common pin (I think - double check) 

Make sure all the pins in the Pinout are giving proper voltage.

This runs the PSU without any load, to help see if it's a PSU problem or not.

Sometimes PSUs won't give a rail, or it's out of tolerance, or it can kill your components.