Recently i helped my dad on his new office PC. it is running on i5-4570, asus h87-plus mobo, 8gb Kingston RAM, 120gb plextor SSD, 2TB seagate HDD, samsung OEM dvd drive, Thermaltake 630w smart series PSU. At first it was fine, all up and running. But a week later, my dad had problem with it, when he tries to boot up the PC, he can hear the fans spinning but no response on monitor, he tried restarting and the PC was able to boot up. But this problem became frequent. Sometimes he had to wait 10~15minutes or even hours to wait for it to be able to boot up. I installed the beep speaker that would indicate the PC is up running, the magic beep. When the system fail to boot up, the speaker would not beep. And worse, the PC just turned off itself while my dad was using it and could not boot up at all, no fans spinning etc. so he brought it back and tried installing my gaming rig PSU instead and the pc was able to boot up but had the some boot up problem like in every 2 shutdown and restarts. I tried using the belived to be spoilt psu on my own system, it had given power to fans, mobo etc but monitor had no response so i tried restarting it but after 3x tries, i could not boot up at all. Back to my dad PC, I also realised that the LED near MEMok does not flash when the system fails to boot. I reseting RTC ram (jumpers) and disabling fast boot options on BIOS. Does anyone how solution to this? Please help me.