[NEED HELP] My ethereum rig just can not boot, mobo ASUS z270a

Hello so my rig contains:

MOBO: Asus z270a prime LGA1151
CPU: Intel pentium G4560 LGA1151 <<< FAN spin when power on
RAM: Kingston 4GB DDR4 2133 CL14 288 - Pin UDIMM
PSU: Corsair RM1000x <<< FAN spin when power on
GPU: MSI gaming rx580 x 6, but I just plug 1 and the MOBO just can not boot.
SimpleminingOS USB

So I assembled my first rig, connect the PSU with the MOBO, both 24pin and 8pin, RAM on the A2 slot, CPU on the right direction, CPU fan plugged in and run well. Everything seems good, but the MOBO just can not boot. I power it up and just see the LED on, the CPU fan running, nothing happen on the monitor.

So I check the 4 LEDS, only the DRAM Led is on, and then I tried to press MEMok button, it does not help, the Dram Led flash, and then still on, which indicate that there is an error.

I tried to Google for hours, it seems many people have the same problems, but no one can have a solution.

So guys, you are my only hope, or tomorrow I will need to go to retailer to check it up.