Newish PC wont boot. cpu dead?

[NanoPIX]

First of all I had this PC:

-Intel Core i5 3570k
-Asrock z77 extreme 4
-Asus rog strix gtx 970
-16 gb RAM G.skill ripjaws

-Corsair cx750

-240gb ssd/1tb hdd

 

I decided to buy a few new parts and use the old ones temporarily until I had all new parts, bought:

-Ryzen 5 2600x
-Asus rog strix b350-f mb
-16gb g.skill aegis

 

PC worked for at least 6h, everything was fine, even tho I didnt upgrade graphics card I could feel the difference in games.

Then, suddenly it turned off.
When I power it up the screens have no reaction, but everything seems to be working. (I rebuilt old pc and I know that the old parts are all working normally(monitors,PSU,GPU,HDDs,SSD))

All the fans work, including cpu and gpu, motherboard LEDs work, etc.

 

I tried everything I could think of:

-Placed one RAM stick at a time, in each slot, different patterns etc...

-Removed graphics card and used onboard graphics

-Replugged every single power supply cable and other cables

-Rebuilt pc entirely

 

Then for some reason I had the idea of unplugging the CPU power supply cabl and booting it like that, exact same result as before, having CPU power supply cable plugged or unplugged makes no difference.

which leads me to think either the CPU is dead or the motherboard is not forwarding power from the cable socket to the CPU?

 

How can I make sure which one is causing this? I dont have any other compatible CPUs/motherboards.

[emosun]

In your motherboard manual it will give you steps to reset the bios , give that a try

[NanoPIX]

Just now, emosun said:

In your motherboard manual it will give you steps to reset the bios , give that a try

forgot to mention I also tried that.

[emosun]

well it's not impossible that it could just be a defective board or cpu , if it was going to die from a defect it does seem consistent with only working for a few hours.

the only other thing i can think of is make sure all the drives are unplugged while you are trying to get it to post

You can also unplug the motherboard entirely and remove the battery for an hour just to make sure it absolutely is loosing it's bios settings