Computer turns itself on after any off mode
Whenever I shut down my computer, or put it in sleep/hybernate, it turns on after two seconds. It doesn't post, it just powers on and then idles. To actually turn it off, I switch off the psu. The problem is now, whenever I switch the psu on and try to boot, it doesn't always turn on. It takes a good amount of flicking the psu switch on and off before the motherboard lights up.
So far I've determined the things its not:
- its not caused by the mouse or network waking up the computer. I've been able to go into hybernate for the past year. And all "wake on X" settings in the bios are diabled.
- its not a scheduled task waking up the computer at a given hour, it occurs every single time
- its not due to an upgrade or new installation, since I haven't done either in a very long time
I'm sure its a hardware issue. So I'd like to know, is my psu dead, or the motherboard? The psu is an Antec Earthwatts 600w, the motherboard is an Asus P5Q-E, both one year old.
While it could be either, the PSU is the more likely candidate, and probably easier/cheaper to replace. Try swapping the PSU out for a known-good (or "new", that works too) PSU of equal or greater wattage.
If your problems disappear, blame the PSU and move on.
This turned out to be two problems.
The problem is now, whenever I switch the psu on and try to boot, it doesn't always turn on. It takes a good amount of flicking the psu switch on and off before the motherboard lights up.
As quack pointed out, the PSU was a likely candidate. It was clearly dying, so I replaced it. Now the power always turned on. However, the following problem remained:
Whenever I shut down my computer, or put it in sleep/hybernate, it turns on after two seconds. It doesn't post, it just powers on and then idles.
While attempting to solve this, I went about the following:
- Cleared the BIOS many, many times
- Tried all possible permutations of bios options relating to power and sleep
- Systematically removing hardware/peripherals and then booting/sleeping, until I ended up with only motherboard, cpu, psu, one stick of ram, and a power cord connected (I scheduled a task that put the computer to sleep one minute after boot to test)
- Investigated the event viewer for problems
- ran powercfg -LASTWAKE to get a report on what woke up the computer
This led me to replace the motherboard. Now I have no problems either booting or sleeping. So in conclusion, the replacement of both the PSU and the motherboard solved the problem.