Help with PC that self-boots

2 month old build. Issue started from day one. PC could have been powered off all day and then just start up on its own. At first it would do this a couple times a week then nearly every day now it does this a couple times a day.

New additional symptom. About a month back I would power on the PC and the boot process would stall. I’d get error message “inaccessible boot device”. Then it would restart and boot just fine.

Mobo_ ROG Impact

CPU_ 4670K

RAM_ Corsair Vengeance LP

PSU_ Thermaltake Smart 650W

HDD_ Seagate Barracuda 1TB (ST1000DM003 7K 64m)

GPU_ Gigabyte GTX660

OS_ Win8

I tried setting BIOS to default settings, no change with issue. The Impact has a “fast-boot” function. I tried enabling and disabling it, no change.  Any thoughts on my problem are appreciated.

Thank you…

I don't know about the self booting problem.

But with the inaccessible boot device problem, it could possibly be that your HDD might be failing, I'd also check the SATA cable you're using, maybe if you have a spare SATA cable, try that out and see if you get the same error or not during boot, otherwise I can't think of much else for this specific problem, hope all is well soon though!

Thanks for the tip. I'm going to change out the SATA cable and check all the other connections. I suspected the BOOT drive might have been bad but did not know if it related to the self-booting issue. 

If anyone else has any thoughts, they’re very welcome...

I've had similar problems, I'm not sure what specifically stops it from turning itself on but what I did was go in to the BIOS and make sure all the wake on lan, wake on event, wake on USB type stuff was disabled, then go in to your advanced power settings in windows, go to multimedia settings and set 'when sharing media' to 'allow the computer to sleep'

Thanks KANE, I'm trying your suggestions. I'll report back my progress ...