I have a PC 1 1/2 years old based on PH77V, motherboard, i5 2500k Intel CPU, 2 x 4 GB DDR3 1600MHz, 650w power supply, 2 SATA hdds and a DVD disk reader/writer
A couple of days ago the PC turned off and on by itself two or three times and then remained dead, I assumed it could be a short someplace.
I tested power supply without load and voltages are within range and I installed the power supply in an older PC and it worked fine
Following ASUS support, I took everything out of the case and reassembly the system, except de dvd and hdds on a “white board” to see if it starts POST
Then I installed the power supply into the PH77V and connected to line voltage the system.
The power and chassis fans run a second and stop and enter in a loop of run a second and stop some 3 seconds and so on, nothing else happens, no beeps.
I changed motherboard battery without any result. There is no sign of damage in MB capacitors
I connected the PH77V to an older 400W ATX power supply that had a 4 pin EATX 12V instead of the 8 pin EATX 12V that the mother board requires (because that possibility is considered by ASSUS support) but the same loop on/off appeared
I don’t know if it is the mother board or the CPU that fails.
Can you give me some ideas on how to follow checking?