Asrock z370 pro4 , core i5 problem

Asrock z370 pro4 , palit 1060 jetstream , core i5 8400 , seasonic s12ii bronze 620w, G.Skill Aegis 16GB DDR4 16GISB K2 3000 C16( 2x8), arctic freezer 7 pro, seagate hdd 1 tb blue, kingston ssd 120
When I turn my new PC on, the case, CPU and GPU fans begin working, the GPU lights up but nothing else happens and I get a "no signal" on my screen( 8 /4pin core and 24/20 pin mother plugged in) The PC doesn't turn off but just remains in this state I've checked all plugs multiple times, removed the GPU and used the motherboard's HDMI,and VGA outputs , tried moving the RAM stick to different slots and booting with 1 ram and no RAM at all (it beeps)

After this im remove cooler recheck socket and processor it looks fine ( cooler tower tightened slightly this time), put everything back and it works! im put gpu back and install windows 10 start update drivers and in one moment( 30 min i guess) PC turn off and goes to same state( no signal)

At this moment i read that it may be bios problem so i removed the CMOS battery for an hour ,Clear CMOS to default and it works for 2 min..then same thing( no signal) Mention 1: at no signal state processor was cold every time 2: this time try without gpu connected( integrated video)

I removed all cables, gpu ,hdd , sdd from mother, exept power for core and mother ,cooler for core and pc power ptn , ram. it won't work( no signal) im remove cooler clear thermal grease, pull out core plugged it again and put stock i5 cooler this time, load bios, update it to 3.10 ( core temperature 35 С), load windows, its works for 20 min, im turn it off insert all stuff again ( even gpu) load it, install couple of programs, not drivers , it took 15-25 minutes , then i turn windows of, screen goes black but pc still working, im wait for couple of minutes nothing change, im restart it with on button and got no signal again( pc works like every time, processor is cold like every time when no signal)

No beeps exept ram remove, i guess not overheat cuz im try 2 different coolers , and it starts working after core reinstall ,what is that mean?
p.s.sry for bad english

Edited by TechnoGear - 03 Sep 2018 at 12:28am

Did you breadboard test the motherboard, cpu and ram before mounting in the case ?
https://www.youtube.com/watch?v=l5ry7smNtPU
https://www.youtube.com/watch?v=aEP3OLZvMm0