Random shutdowns, checked everything, help

[MattN]

I spent almost a week trying to figure out why my computer shutting down randomly instantly, as if someone pulled the power cord. It can last for up to 2 hours or 2 seconds after pressing the power button.

I built this gaming rig 1.5 year ago, it can still easily runs the most demanding games out there. I don't want to waste money replacing parts unless I'm absolutely sure. So I need everyone's opinions.

First I thought it was software related error, so I went into cmos mode, and it still shutting down, so I figured it most like hardware related. I unplugged all hard drives, dvd drive, and tried again just to be really sure it's hardware, still shuts down. I thought maybe if the cpu was overheat, so I let it sit in cmos mode and watch the cpu temp, it was around 39-45C, that's normal. I bought a brand new power supply and it still shuts down randomly!!! I took out all memory sticks but 1 and switch in between and took out the graphic card too, and still it shuts down!!! I checked all the capacitors in my motherboard, blow all the dusts, checked for cracks, and nothing out of the ordinary.

My question is wth is wrong with my computer? Help!!!!!!!!!!!!!!

I probably already answered my question, that it's probably the motherboard, but I want to be sure if there's something else.

 

[Tmagic650]

Yes, it is most likely the motherboard...

 

[MattN]

Ok, I just bought a new motherboard. I wished I knew it sooner, so I don't have to waste money on a new power supply. I suspect it was either PS or mobo, but took a chance and bought PS first b/c it's cheaper.

The new mobo fixed the random shutdown. But....

Would a dead cmos 3V battery causing random instant shutdowns? I noticed there's no beep when I did a hard boot to power on, or when I shut it down. And the VU gauge meter jumped to max when windows start then dropped back (don't know what's the VU is for).

Don't tell me I could have just buy a 3V battery instead of spending over 250 for parts. Arghhh!