Hi, for a while now my pc (5 year old, desktop ASUS ROG G20 AJ)  has been worrying me, and I can't identify the issue. Until now since the problem started, it was just that only once unplugged, on startup my pc would show the American Megatrends screen and the chasis LEDs would reset their settings. I've been reading about other similar issues on other people's systems, and concluded that it was probably a CMOS battery failure.


From what I've read, the most TROUBLE it would give me would be having to set the time and date and GOING through the BIOS screen I mentioned. In my PC, date and time do NOT reset. I've set them to be managed via internet, so I don't know if that means something or makes a difference. I've bought a CMOS battery just in case I find myself in the absolute necessity of changing it, but i'm really afraid to mess up something and not even knowing what mistake I made, so I was willing to keep it like that.


This problem recently extended to happening even when keeping the pc plugged between uses (shut down). Also, while sleeping, once I wake the system up it just acts as a regular boot from complete shut down, even when the power button was lit up (meaning the pc is on). This also has the same chasis LEDs and BIOS screen business.


I've opened the system log, and while I cannot really understand all the info available, there was one entry regarding the sleep wake up-startup instance, tiled "Critical" that read "The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly." I am 100% sure that the power did not go out, and as I said, all the signs pointed to a regular, healthy sleep until the troubled waking up.


My OS is Windows 8.1, keep it up to date, ran antivirus and if it is of any use or indication of wrongdoing to my pc wellbeing, my regular schedule is aproximately 16h of activity, with regular sleep periods (2 h) while I attend other business. Shut down every day until next use. No problems, change of behavior, sudden restarts or *censored* downs while actively using it whatsoever.
Replace the battery already...Thank you for replying, but I'd like to identify the issue if it's possible before rushing and messing the system further. I have no experience in manipulating internal hardware, and there is the possibility that what's happening is crystal clear for someone with more experience than me and maybe fixable without having to retort to that.

As I said, it seemed to me initially that it was a CMOS battery issue, but from what I read, some of the symptoms escape the usual diagnostics.Replacing the cmos battery is a 5 minute job for ANYONE. It is most likely the cause of your problem - as Patio suggested above, go ahead and replace it. It certainly won't do any harm.Also as you computer was supplied with a 128GB ssd  as the system drive it would pay to check you have plenty of FREE space like you are only using 100GB of the drive. Any more and you may have issues with windows hibernation file,  which on your system could use 16 GB of the ssd space. Also i would run HD sentinel on the drive as at 5 years the Kingston SSD could be close to end of life.

https://www.hdsentinel.com/download.php

Well, I tried today to open the pc and follow your advice, but to reach the battery in this model I have to remove ALMOST literally all the rest of the components. Tried to find my way through it, but it got to a point in which I had to remove several delicate cables from the motherboard in compact spaces, and decided to assemble it back.

I had to do it twice since the first time I obviously messed up and the BIOS wouldn't even boot, much to my temporary agony and regret. I tried resetting the CMOS with the jumper, tho, but the results remain to be seen.

I know that this same model had variants. In my case the system drive is an HDD, always has PLENTY of free space. Ran CrystalDiskInfo and all the disks are healthy.

Lesson learned about the downsides of prebuilt PCs, I guess...