9010 SFF, PSU problem?

Hello to everybody,

I have a OptiPlex with I7 + 16 GB ram + GTX 1050ti and 1TB SSD.

Computer was working flawlessly, but after I turned off my pc the next day light will be amber and blink twice then pause and then twice.

If I hold the button on the PSU computer works without any problem but if I leave the button the PC turn off and start again blinking amber. I tried to update bios, disconnect and reconnect all the devices individually but problem still persist. 

I tried to test the PSU with the jumper from green to black and PSU will turn on.

So can anyone say me if the problem is the PSU or motherboard?

Thank You to everybody for help.

Mike