CMOS Checksum bad - AsRock 890GX Extreme 4

[Inskriptor]

Hello.

So I recently encountered in this problem: every time by turning on my PC, at POST screen it says "CMOS checksum bad" - and the BIOS settings are reset, but the date and time is working perfectly (it's not resetted).
What I done so far:

• 
  ■ Replaced with a brand new battery (voltages are ok, via multimeter)
  ■Scratched the metal parts of the CMOS reset jumper and the battery seat aswell to remove any oxidation.
  ■Re-seated every module inside and outside my pc (peripherials, disks, psu, vga etc...)
  ■Left only my SSD inside the PC and did a windows repair
  ■Plugged back my other HDD
  ■Resetted CMOS 10000x times
  ■Installed another CMOS battery (CR2032)
  ■Resetted CMOS via jumper (yes it's on its correct place now)
  ■Resetted CMOS with "Reset CMOS button on the MOBO, and from the Back of the PC (External MOBO button)

Everything worked normally for estimatedly 1 days.
Today it started over. I instantly knew that the CMOS resetted itself again, when I turned on my pc and the fans were on 100% speed again. Weirdest stuff: BIOS settings are resetted, but the date and time is perfect - it's showing the correct times.
The problem will start when I turn my pc off, and shut my UPS down (APC UPS, that's working perfectly). Basically I leave my PC on it's own CR2032 for a night. I did this for 1years without any problems. Suddenly this "CMOS checksum bad" just came, and I just can't figure out what the heck is this. I have experience in basic repairing, and I think that I tried out everything. You guys are my last hope, please don't tell me that my cmos chip is bad 🙁
Infos about my rig
OS: Windows 10
SSD: Kingston 120GB (AHCI mode enabled) (bought in this year's april)
HDD: Toshiba 1TB SATA3 (bought in this year's april aswell).
Mobo: Asrock 890gx extreme4 (bought in 2010's)
DDR3: 2x 4GB and 2x 2GB Kingston HyperX (bought the 2x 4 in april of this year)
PSU: Corsair 650W (2010)
CPU: AMD Phenom II x4 (2010)
VGA: Gigabyte GT630 2GB
UPS: APC (since previous year's xmas)

Bios is up to date to 1.3 (latest) AMI Bios - working since release (2014) so I don't think this is the cause.
Voltages are normal, PSU is Corsair (quality) - So as you can see, my rig is not that budget money saving build.
No overheats, everything is on normal level.

There was NO electric surge in the past half year, not even thunderstorms.. +I always unplug my pc from the AC before going to sleep, so it's safe for the night. I even unplug it from ODT terminal, so thunderstorm surge can't go through the optical wire /or RJ45 😛 (Just in case) 😀 I know I'm a bit too safety maniac, but this is why my pc is still healthy afterall (except this issue ofc).

Basically my PC is working normally after I set all the configs in the BIOS, but this is very annoying that I have to set it over and over again. +the thoughts that I might working on a failing system, makes my head ache :S

Oh, one more note: If I don't turn off the UPS then everything is ok - no cmos checksum bad error messages. So for me it seems that the MOBO doesn't get any power from the battery when it's "alone". If I turn the UPS off and leave it "alone" for 1+ hours then the BIOS settings are reset. The weirdest stuff, is still that the date and time component still remains.

Please, I'd appreciate some help from you guys. Perhaps my BIOS is corrupted with a virus?

 

[Multipack]

Probably not a virus but it could have an outdated/corrupt ME driver version etc. Sounds like you have tried most things I could suggest, but maybe an expert can offer further insight. Have you updated all of your drivers? Maybe it's time to send your MB for proper diagnostics. Sounds like it's half-bricked..

 

[Inskriptor]

I did nothing in the past year, not even upgrading my bios - it's the latest version. The only thing changed on my computer was a SSD installation and 2 new rams, but they were operating perfectly since april. I won't bother sending my mobo for diagnosis, it's too old, I wanted to replace it anyways, I'm just seeking for a solution so if I meet this problem again in the future, I'll know how to fix it Yeah I was thinking the same, that my mobo is bricked, but I don't have any idea - why. This problem just popped up randomly from nowhere. I would understand if this problem pops up right after I change something in my PC, but I haven't touched it since a while :S ME driver? Isn't it for Intel? Coz I have AMD based rig. :3

 

[Multipack]

Lol oh yeah. I really should check these things.. but yeah almost definitely a mobo problem. They can just happen after time I guess. I have MB's working that are 5+ years old and have had some go on me after 3 months. Any signs of physical damage? Capacitors etc? Is a professional job at this point tbh.

 

[Inskriptor]

Yeah :/ Oh well, I'll wait a little bit more for more suggestions. Perhaps there's one last hope 😀 I'm trying to hold my current mobo's life like a bastion - "inhaling some spirit" in it, because I don't wanna waste money if there's a little hope, but if everything fails, then there I go... I'll probably buy a Gigabyte mobo :3

 

[Inskriptor]

Any ideas? Update: my system randomly gets a blue screen, restarts, and then everything is resetted again (except date and time, those are working perfectly)
LOL..

 

[Inskriptor]

Alright - thank God I figured it out! 😉

 

[Capt_Flint]

Alright - thank God I figured it out! 😉

Please share how you fixed the "CMOS checksum bad" issue.
I have ASRock 890GM Pro3 motherboard with same problem.
Thanks.