Computer restarts when booting

[alphasam123]

My CPU and case fans turn on and off when booting, the computer is not displaying anything.

My pc turned off the other day by itself, the motherboard LEDs would light, but pressing the power button did nothing.

I have now replaced the power supply and now when starting the fans start up, stop, start, stop, and then keep running until the power is turned off, there is no video being outputted to my monitor.

I have changed the motherboard to a new one (I assumed the PSU must have broken another component when failing, but the same problems still occur).

I have tried with each stick of ram to no success, however, with no RAM the fans just spin and don't stop (still no video output).

There are never any beeps or flashes to indicate what the problem is.

Specs:
Gigabyte AB350M Gaming 3 motherboard
AMD athlon x4 950
2x Crucial CT8G4DFS824A 8 GB DDR4 Memory
(new) corsair 550W gold + power supply
Graphics cards and hard drives have been removed to test what the fault is.

 

[cin19]

My pc turned off the other day by itself, the motherboard LEDs would light, but pressing the power button did nothing.

I have now replaced the power supply and now when starting the fans start up, stop, start, stop, and then keep running until the power is turned off, there is no video being outputted to my monitor.

What are the old PSU and the GPU did you use? If the old PSU died because it cannot handle your GPU, it may or may not kill other pc components.

Graphics cards and hard drives have been removed to test what the fault is.

When you test the PC, you have to use the Discrete GPU, because either MB or athlon x4 950 does not have iGPU.

Now try one more time. Add the GPU back, remove the HDD/RAM, clear the COMS, boot the PC to see what happens. During the boot, you need to open the case, watch the "Status LEDs" for CPU/VGA/DRAM/BOOT, check the manual page 19( https://www.gigabyte.com/us/Motherboard/GA-AB350-Gaming-3-rev-1x#support-manual ), to see which LED is on or not. And you may know what is going on, if the RAM LED is on, add the RAM and boot again.