8 pin CPU Power - Mobo not starting up? ;(

[tdkmatt]

Hey All

i have a new build im doing for my nephew that isnt going too well. after installing all of the parts into the case and turning it on the power comes on and then off right away and sometimes the red cpu light flashes for an instant, i diagnosed it to the 8 pin power on the CPU when its not installed the board and everything will spin up - but funny enough the fan header just below the io ports does not have power to it so im not sure if it gets power from the 8 pin or not.

Tried everything, no ram (doesnt beep) - cleared cmos, tried it out side of the case and same thing. the CPU pins are all fine no damage i even went back and used the CPU install tool. PSU is fine jumping it powers it on. etc..... at this point i think i might either be the CPU or mobo?

Z370-F
Intel i5-6500
Team Group Elite 4GB DDR4 2400 CL 16-16-16-39 1.2V (X2)
MSI GTX1050
Samsung 860 Evo
Corsair RM650X


Any help would be appreciated

[Raja]

Take the board out of the case and set it up on a non-conductive surface, then see what happens.

[tdkmatt]

Yep one of the first things I tried no luck. Its out of the case now still not working cpu fan spins IP cpu led flashes for 1 second and it all turns off. If I power it on without the 8 pin it will all stay on. I dont have a spare cpu or mobo to test with

[xeromist]

Really no way to tell just by that symptom as it could be the PSU, CPU, or motherboard. You pretty much have to swap parts to isolate the fault. You may want to remove the CPU and make sure that neither the CPU nor the socket are damaged/contaminated. That's free to test.