Hi everyone. I have a 3 year old I7 4770K build, with the following components: HAF 932 Full Tower Case, ASUS Z87 Sabertooth Motherboard, EVGA GTX 970 GPU, Corsair TX750M 750watt GPU, 8 GB GSKILL F3-2400C9D RAM, and a 27" LG 29UM67P LCD monitor. I run a stable 4.2ghz overclock that has run without major problems all this time, but recently I found my monitor was blank showing no signal and stuck in sleep mode. The display would not reappear matter what I tried, yet the computer itself was still on and running as normal. At that time I figured I had a monitor or DVI-D cable issue.
I then powered off the pc and monitor to diagnose the problem. Upon starting the pc back up, it refused to boot up as normal. It started with all fans powering on as normal, but it then begins to restart on its own about 2 or 3 times, and subsequently reboots with the display blank and only the CPU and top case fan spinning.
After a few further reboot attempts, I finally see a POST screen. It reports that overclocking failed, so I go inside the BIOS settings to see if I can recover my saved overclock profile. Unfortunately the rebooting cycle continues, except this time it comes back with another POST error message: "SIO Power OK delay failed". I again go into the bios settings, this time in an attempt to get back to the default cpu clock profile but it reboots again. Another reboot or two I actually get as far as the windows 10 logo screen but it abruptly reboots without the POST screen and with just the CPU/top case fan on.
I took of the case to see if any of the mobo LEDS are indicating any issues. This ASUS board has POST State LEDS to indicate any detected faults for the CPU, VGA, Boot Device and RAM, and none of them are on to indicate any issues. Motherboard Standby power LED is green, which is normal, so the mobo appears to be working ok and getting some power from the PSU.
I am thinking the 3 and 1/2 year old PSU (purchased in November 2012) may have gone bad. I am surprised because I never shut down this pc, and I always leave it on or on sleep mode to avoid wear and tear on the components from constant boots. Is the "SIO Power OK delay failed" error specific to a faulty PSU or could this also be related to the motherboard or other components? The PC and monitor is plugged in to a high quality APC surge protector, with it's own status light lit a steady green indicating it is working normally. Is it possible the PSU absorbed some damage from a power spike that the surge protector failed to intercept? I am trying to figure out if its the PSU or mobo that is working incorrectly.